Imaging system lens assembly, imaging apparatus and electronic device

ABSTRACT

An imaging system lens assembly includes four lens elements, the four lens elements are, in order from an object side to an image side along an optical path: a first lens element, a second lens element, a third lens element and a fourth lens element. Each of the four lens elements has an object-side surface towards the object side and an image-side surface towards the image side. The second lens element has negative refractive power, the object-side surface of the second lens element is concave in a paraxial region thereof. The object-side surface of the third lens element is convex in a paraxial region thereof, the image-side surface of the third lens element is concave in a paraxial region thereof.

RELATED APPLICATIONS

This application claims priority to Taiwan Application Serial Number 111112037, filed Mar. 29, 2022, which is herein incorporated by reference.

BACKGROUND Technical Field

The present disclosure relates to an imaging system lens assembly and an imaging apparatus. More particularly, the present disclosure relates to an imaging system lens assembly and an imaging apparatus with compact size applicable to electronic devices.

Description of Related Art

With recent technology of semiconductor process advances, performances of image sensors are enhanced, so that the smaller pixel size can be achieved. Therefore, optical lens assemblies with high image quality have become an indispensable part of many modern electronics. With rapid developments of technology, applications of the electronic devices equipped with optical lens assemblies become wider, and there is a bigger variety of requirements for the optical lens assemblies. However, in a conventional optical lens assembly, it is hard to balance among image quality, sensitivity, aperture size, volume or field of view.

In recent years, with the demands of compact electronic devices, conventional photographing lens assembly is unable to satisfy both requirements of high-end specification and compactness, especially the micro lens assembly with a large aperture stop or a telephoto feature. Because the requirements of the optical zoom become higher (such as increasing the optical zoom ratio), the conventional telephoto lens assemblies cannot satisfy the requirements (due to the excessive total track length, the small aperture stop, the poor image quality or lacking of compactness), so that the arrangements with different optical properties or the ability to fold the optical axis are needed. In order to solve the aforementioned technical problems and demands, an optical lens assembly is provided in the present disclosure to meet the requirements.

SUMMARY

According to the present disclosure, an imaging system lens assembly includes four lens elements, the four lens elements are, in order from an object side to an image side along an optical path: a first lens element, a second lens element, a third lens element and a fourth lens element. Each of the four lens elements has an object-side surface towards the object side and an image-side surface towards the image side. The second lens element preferably has negative refractive power, the object-side surface of the second lens element preferably is concave in a paraxial region thereof. The object-side surface of the third lens element preferably is convex in a paraxial region thereof, the image-side surface of the third lens element preferably is concave in a paraxial region thereof. The imaging system lens assembly preferably further includes an aperture stop. When an axial distance between the aperture stop and the image-side surface of the fourth lens element is SD, a curvature radius of the object-side surface of the second lens element is R3, a curvature radius of the image-side surface of the second lens element is R4, an axial distance between the object-side surface of the first lens element and the image-side surface of the fourth lens element is TD, an axial distance between the image-side surface of the fourth lens element and an image surface is BL, a sum of all axial distances between adjacent lens elements of the imaging system lens assembly is ΣAT, a sum of all central thicknesses of the four lens elements of the imaging system lens assembly is ΣCT, a focal length of the first lens element is f1, a focal length of the second lens element is f2, a focal length of the third lens element is f3, and a focal length of the fourth lens element is f4, the following conditions preferably are satisfied: (R3+R4)/(R3−R4)<0; 0.1<SD/TD<2.0; 0.1<TD/BL<1.0; 0.04<ΣAT/ΣCT<0.8; 0<|f2/f4|<1.4; and 0.18<|f1/f3|+|f1/f4|<1.75.

According to the present disclosure, an imaging apparatus includes the aforementioned imaging system lens assembly and an image sensor, and the image sensor is disposed on the image surface of the imaging system lens assembly.

According to the present disclosure, an electronic device includes the aforementioned imaging apparatus.

According to the present disclosure, an imaging system lens assembly includes four lens elements, the four lens elements are, in order from an object side to an image side along an optical path: a first lens element, a second lens element, a third lens element and a fourth lens element. Each of the four lens elements has an object-side surface towards the object side and an image-side surface towards the image side. The second lens element preferably has negative refractive power, the object-side surface of the second lens element preferably is concave in a paraxial region thereof. The object-side surface of the third lens element preferably is convex in a paraxial region thereof, the image-side surface of the third lens element preferably is concave in a paraxial region thereof. There preferably is an air gap between each of adjacent lens elements of the four lens elements of the imaging system lens assembly. The imaging system lens assembly preferably further includes an aperture stop. When an axial distance between the aperture stop and the image-side surface of the fourth lens element is SD, a curvature radius of the object-side surface of the second lens element is R3, a curvature radius of the image-side surface of the second lens element is R4, an axial distance between the object-side surface of the first lens element and the image-side surface of the fourth lens element is TD, an axial distance between the image-side surface of the fourth lens element and an image surface is BL, an axial distance between the first lens element and the second lens element is T12, an axial distance between the second lens element and the third lens element is T23, a focal length of the second lens element is f2, a focal length of the fourth lens element is f4, a central thickness of the first lens element is CT1, a central thickness of the third lens element is CT3, and a central thickness of the fourth lens element is CT4, the following conditions preferably are satisfied: (R3+R4)/(R3−R4)<0; 0.1<SD/TD<2.0; 0.1<TD/BL<1.0; 0.01<T23/T12<30.0; 0<|f2/f4|<0.95; and 0.1<(CT3+CT4)/CT1<1.5.

According to the present disclosure, an imaging system lens assembly includes four lens elements, the four lens elements are, in order from an object side to an image side along an optical path: a first lens element, a second lens element, a third lens element and a fourth lens element. Each of the four lens elements has an object-side surface towards the object side and an image-side surface towards the image side. The second lens element preferably has negative refractive power, the object-side surface of the second lens element preferably is concave in a paraxial region thereof. The object-side surface of the third lens element preferably is convex in a paraxial region thereof, the image-side surface of the third lens element preferably is concave in a paraxial region thereof. When a curvature radius of the object-side surface of the second lens element is R3, a curvature radius of the image-side surface of the second lens element is R4, an axial distance between the object-side surface of the first lens element and the image-side surface of the fourth lens element is TD, an axial distance between the image-side surface of the fourth lens element and an image surface is BL, an axial distance between the first lens element and the second lens element is T12, an axial distance between the second lens element and the third lens element is T23, a focal length of the imaging system lens assembly is f, a focal length of the first lens element is f1, a focal length of the second lens element is f2, and a focal length of the fourth lens element is f4, the following conditions preferably are satisfied: (R3+R4)/(R3−R4)<0; 0.1<TD/BL<1.0; 0.01<T23/T12<20.0; −10.5<f/f2<−0.75; and 0<|f1/f4|<0.87.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure can be more fully understood by reading the following detailed description of the embodiment, with reference made to the accompanying drawings as follows:

FIG. 1 is a schematic view of an imaging apparatus according to the 1st embodiment of the present disclosure.

FIG. 2 shows, in order from left to right, spherical aberration curves, astigmatic field curves and a distortion curve of the imaging apparatus according to the 1st embodiment.

FIG. 3 is a schematic view of an imaging apparatus according to the 2nd embodiment of the present disclosure.

FIG. 4 shows, in order from left to right, spherical aberration curves, astigmatic field curves and a distortion curve of the imaging apparatus according to the 2nd embodiment.

FIG. 5 is a schematic view of an imaging apparatus according to the 3rd embodiment of the present disclosure.

FIG. 6 shows, in order from left to right, spherical aberration curves, astigmatic field curves and a distortion curve of the imaging apparatus according to the 3rd embodiment.

FIG. 7 is a schematic view of an imaging apparatus according to the 4th embodiment of the present disclosure.

FIG. 8 shows, in order from left to right, spherical aberration curves, astigmatic field curves and a distortion curve of the imaging apparatus according to the 4th embodiment.

FIG. 9 is a schematic view of an imaging apparatus according to the 5th embodiment of the present disclosure.

FIG. 10 shows, in order from left to right, spherical aberration curves, astigmatic field curves and a distortion curve of the imaging apparatus according to the 5th embodiment.

FIG. 11 is a schematic view of an imaging apparatus according to the 6th embodiment of the present disclosure.

FIG. 12 shows, in order from left to right, spherical aberration curves, astigmatic field curves and a distortion curve of the imaging apparatus according to the 6th embodiment.

FIG. 13 is a schematic view of an imaging apparatus according to the 7th embodiment of the present disclosure.

FIG. 14 shows, in order from left to right, spherical aberration curves, astigmatic field curves and a distortion curve of the imaging apparatus according to the 7th embodiment.

FIG. 15 is a schematic view of an imaging apparatus according to the 8th embodiment of the present disclosure.

FIG. 16 shows, in order from left to right, spherical aberration curves, astigmatic field curves and a distortion curve of the imaging apparatus according to the 8th embodiment.

FIG. 17 is a schematic view of an imaging apparatus according to the 9th embodiment of the present disclosure.

FIG. 18 shows, in order from left to right, spherical aberration curves, astigmatic field curves and a distortion curve of the imaging apparatus according to the 9th embodiment.

FIG. 19 is a three-dimensional schematic view of an imaging apparatus according to the 10th embodiment of the present disclosure.

FIG. 20A is a schematic view of one side of an electronic device according to the 11th embodiment of the present disclosure.

FIG. 20B is a schematic view of another side of the electronic device of FIG. 20A.

FIG. 20C is a system schematic view of the electronic device of FIG. 20A.

FIG. 21 is a schematic view of one side of an electronic device according to the 12th embodiment of the present disclosure.

FIG. 22 is a schematic view of one side of an electronic device according to the 13th embodiment of the present disclosure.

FIG. 23A is a schematic view of one side of an electronic device according to the 14th embodiment of the present disclosure.

FIG. 23B is a schematic view of another side of the electronic device of FIG. 23A.

FIG. 24A is a schematic view of an arrangement of a light path folding element in the imaging system lens assembly of the present disclosure.

FIG. 24B is a schematic view of another arrangement of the light path folding element in the imaging system lens assembly of the present disclosure.

FIG. 24C is a schematic view of an arrangement of two light path folding elements in the imaging system lens assembly of the present disclosure.

FIG. 24D is a schematic view of another arrangement of the two light path folding elements in the imaging system lens assembly of the present disclosure.

FIG. 24E is a schematic view of one another arrangement of the light path folding element in the imaging system lens assembly of the present disclosure.

DETAILED DESCRIPTION

According to the present disclosure, an imaging system lens assembly includes four lens elements, the four lens elements are, in order from an object side to an image side along an optical path: a first lens element, a second lens element, a third lens element and a fourth lens element. Each of the four lens elements has an object-side surface towards the object side and an image-side surface towards the image side.

The first lens element can have positive refractive power, which is favorable for reducing the volume of the imaging system lens assembly. The object-side surface of the first lens element can be convex in a paraxial region thereof, so as to adjust the refractive power of the first lens element.

The second lens element has negative refractive power, so as to correct the aberrations of the imaging system lens assembly. The object-side surface of the second lens element is concave in a paraxial region thereof, so as to balance the spherical aberrations and coma aberrations of the imaging system lens assembly.

The object-side surface of the third lens element is convex in a paraxial region thereof, so as to improve the symmetry of the imaging system lens assembly, and the image quality can be enhanced. The image-side surface of the third lens element is concave in a paraxial region thereof, which helps to reduce the back focal length of the imaging system lens assembly and correct aberrations in the off-axis region at the same time.

There can be an air gap between each of adjacent lens elements of the four lens elements of the imaging system lens assembly. Therefore, the simplicity of assembling the imaging system lens assembly can be ensured, which improves the yield of assembling.

At least one of the object-side surface and the image-side surface of at least one of the four lens elements can include at least one inflection point. Therefore, the distortion can be corrected, which prevents the image at the peripheral region from deformation.

The imaging system lens assembly can further include a reflective element, which can be disposed between an imaged object and an image surface. Therefore, it can provide a different light path for the imaging system lens assembly. The space arrangement of the imaging system lens assembly can be more flexible, which is favorable for reducing the structural limitations and for compactness of the imaging system lens assembly. Moreover, the reflective element can be disposed at an object side of the object-side surface of the first lens element or at an image side of the image-side surface of the fourth lens element.

The imaging system lens assembly can further include an aperture stop, which can be disposed between the imaged object and the second lens element. Therefore, the imaging region and the incident angle of light incident on the image surface can be limited, and the function of photography from afar and the effect of high imaging brightness can be satisfied simultaneously.

When a curvature radius of the object-side surface of the second lens element is R3, and a curvature radius of the image-side surface of the second lens element is R4, the following condition is satisfied: (R3+R4)/(R3−R4)<0. Therefore, the refraction of the object-side surface of the second lens element can be stronger, so as to control the light path. Moreover, the following condition can be satisfied: −10.0<(R3+R4)/(R3−R4)<0. Furthermore, the following condition can be satisfied: −5.0<(R3+R4)/(R3−R4)<−0.2.

When an axial distance between the object-side surface of the first lens element and the image-side surface of the fourth lens element is TD, and an axial distance between the image-side surface of the fourth lens element and the image surface is BL, the following condition is satisfied: 0.1<TD/BL<1.0. Therefore, it makes sure that the imaging system lens assembly can perform better telephoto ability. Moreover, the following condition can be satisfied: 0.25<TD/BL<0.85.

When an axial distance between the aperture stop and the image-side surface of the fourth lens element is SD, and the axial distance between the object-side surface of the first lens element and the image-side surface of the fourth lens element is TD, the following condition is satisfied: 0.1<SD/TD<2.0. Therefore, the position of the aperture stop can be controlled, so as to maintain a smaller aperture at the object side of the imaging system lens assembly. Moreover, the following condition can be satisfied: 0.1<SD/TD<1.6. Furthermore, the following condition can be satisfied: 0.3<SD/TD<1.3.

When a sum of all axial distances between adjacent lens elements of the imaging system lens assembly is ΣAT, and a sum of all central thicknesses of the four lens elements of the imaging system lens assembly is ΣCT, the following condition is satisfied: 0.04<ΣAT/ΣCT<0.8. Therefore, the distribution of the lens elements can be adjusted and a balance between the thickness and the gap of the lens elements can be achieved, which is favorable for reducing the volume.

When a focal length of the second lens element is f2, and a focal length of the fourth lens element is f4, the following condition is satisfied: 0<|f2/f4|<1.4. Therefore, the arrangement of refractive power can be properly set up, so as to control the back focal length of the imaging system lens assembly, and further satisfy the various applications. Moreover, the following condition can be satisfied: 0<|f2/f4|<1.05. Furthermore, the following condition can be satisfied: 0<|f2/f4|<0.95.

When a focal length of the first lens element is f1, a focal length of the third lens element is f3, and the focal length of the fourth lens element is f4, the following condition is satisfied: 0.18<|f1/f3|+|f1/f4|<1.75. Therefore, it makes sure that the first lens element has sufficient refractive power to fulfill the compact feature of the imaging system lens assembly.

When half of a maximum field of view of the imaging system lens assembly is HFOV, the following condition is satisfied: 5.0 degrees<HFOV<20.5 degrees. Therefore, a suitable field of view can be given to the imaging system lens assembly for the telephoto applications. Moreover, the following condition can be satisfied: 7.0 degrees<HFOV<18.0 degrees.

When a central thickness of the first lens element is CT1, and a central thickness of the fourth lens element is CT4, the following condition is satisfied: 0.1<CT4/CT1<0.8. Therefore, the central thickness of the first lens element and the ratio can be controlled, so as to prevent the excessive height of the imaging system lens assembly.

When a focal length of the imaging system lens assembly is f, and the focal length of the second lens element is f2, the following condition is satisfied: −10.5<f/f2<−0.75. Therefore, the refractive power of the second lens element can be adjusted, which is favorable for correcting the aberrations and adjusting the field of view. Moreover, the following condition can be satisfied: −7.5<f/f2<−1.0. Furthermore, the following condition can be satisfied: −4.5<f/f2<−1.4.

When an Abbe number of the second lens element is V2, and an Abbe number of the fourth lens element is V4, the following condition is satisfied: 0.01<V4/V2<2.5. Therefore, it is favorable for enhancing the correction of chromatic aberration. Moreover, the following condition can be satisfied: 0.1<V4/V2<2.0.

When an axial distance between the first lens element and the second lens element is T12, and an axial distance between the second lens element and the third lens element is T23, the following condition is satisfied: 0.01<T23/T12<30.0. Therefore, the lens elements can cooperate with each other, so as to reduce the volume of the lens elements. Moreover, the following condition can be satisfied: 0.01<T23/T12<20.0. Furthermore, the following condition can be satisfied: 0.1<T23/T12<10.0.

When the central thickness of the first lens element is CT1, a central thickness of the third lens element is CT3, and the central thickness of the fourth lens element is CT4, the following condition is satisfied: 0.1<(CT3+CT4)/CT1<1.5. Therefore, the third lens element and the fourth lens element can cooperate with each other, which is favorable for reducing the volume of the lens elements. Moreover, the following condition can be satisfied: 0.35<(CT3+CT4)/CT1<1.3.

When an f-number of the imaging system lens assembly is Fno, the following condition is satisfied: 2.0<Fno<4.5. Therefore, a balance between the illuminance and the depth of field can be achieved, and the image quality can be enhanced by increasing the amount of incident light.

When the focal length of the second lens element is f2, and a central thickness of the second lens element is CT2, the following condition is satisfied: −10.0<f2/CT2<−3.0. Therefore, the refractive power and the thickness of the lens elements can be effectively balanced, which is favorable for correcting the aberrations of the imaging system lens assembly and for compactness of the imaging system lens assembly.

When the central thickness of the second lens element is CT2, and the central thickness of the fourth lens element is CT4, the following condition is satisfied: 0.1<CT4/CT2<1.0. Therefore, the ratio of the central thicknesses of the second lens element and the fourth lens element can be balanced, so as to control the volume of the imaging system lens assembly. Moreover, the following condition can be satisfied: 0.3<CT4/CT2<1.0.

When the central thickness of the first lens element is CT1, and the central thickness of the third lens element is CT3, the following condition is satisfied: 0.1<CT3/CT1<1.0. Therefore, the ratio of the central thicknesses of the first lens element and the third lens element can be balanced, so as to control the volume of the imaging system lens assembly. Moreover, the following condition can be satisfied: 0.1<CT3/CT1<0.8.

When the focal length of the first lens element is f1, and the focal length of the fourth lens element is f4, the following condition is satisfied: 0<|f1/f4|<0.87. Therefore, the focusing ability at the object side of the imaging system lens assembly and the balance of correcting the chromatic aberration can be enhanced, which is favorable for forming a telephoto system.

When a curvature radius of the object-side surface of the first lens element is R1, and a curvature radius of the image-side surface of the first lens element is R2, the following condition is satisfied: 0<|R1/R2|<0.7. Therefore, the refraction of the object-side surface of the first lens element can be stronger, which is favorable for light convergence so as to reduce the volume of the lens element. Moreover, the following condition can be satisfied: 0<|R1/R2|<0.5.

When a height of a maximum effective radius of the object-side surface of the first lens element is Y1 R1, and a height of a maximum effective radius of the image-side surface of the fourth lens element is Y4R2, the following condition is satisfied: 0.7<Y1 R1/Y4R2<1.6. Therefore, it is favorable for controlling the beam size, so as to avoid an overly large effective radius of the lens elements which will affect the compactness of the imaging system lens assembly.

Each of the aforementioned features of the imaging system lens assembly can be utilized in various combinations for achieving the corresponding effects.

According to the imaging system lens assembly of the present disclosure, the lens elements thereof can be made of glass or plastic materials. When the lens elements are made of glass materials, the distribution of the refractive power of the imaging system lens assembly may be more flexible to design. The glass lens element can either be made by grinding or molding. When the lens elements are made of plastic materials, manufacturing costs can be effectively reduced. Furthermore, surfaces of each lens element can be arranged to be spherical or aspheric (ASP), wherein it is easier to fabricate the spherical surface. If the surfaces are arranged to be aspheric, more controllable variables can be obtained for eliminating aberrations thereof, and to further decrease the required amount of lens elements in the imaging system lens assembly. Therefore, the total track length of the imaging system lens assembly can also be reduced. The aspheric surfaces may be formed by plastic injection molding or glass molding.

According to the imaging system lens assembly of the present disclosure, one or more of the lens material may optionally include an additive which provides light absorption or light interference, so as to alter the lens transmittance in a specific range of wavelength for reducing unwanted stray light or color deviation. For example, the additive may optionally filter out light in the wavelength range of 600 nm-800 nm for reducing excessive red light and/or near infra-red light, or may optionally filter out light in the wavelength range of 350 nm-450 nm to reduce excessive blue light and/or near ultra-violet light from interfering the final image. The additive may be homogenously mixed with plastic material to be used in manufacturing a mixed-material lens element by injection molding. Furthermore, the additive may be added in the coating on the lens element surface to achieve the aforementioned effects.

According to the imaging system lens assembly of the present disclosure, when a surface of a lens element is aspheric, it indicates that the surface has an aspheric shape throughout its optically effective area or a portion(s) thereof.

According to the imaging system lens assembly of the present disclosure, when the lens element has a convex surface, it indicates that the surface can be convex in the paraxial region thereof. When the lens element has a concave surface, it indicates that the surface can be concave in the paraxial region thereof. According to the imaging system lens assembly of the present disclosure, the refractive power or the focal length of a lens element being positive or negative may refer to the refractive power or the focal length in a paraxial region of the lens element.

According to the imaging system lens assembly of the present disclosure, the barrel member or the lens elements can be trimmed, so as to improve the property of reducing the uniaxial size. It is favorable for reducing the volume of the lens elements and further facilitating the compactness of the imaging system lens assembly.

According to the imaging system lens assembly of the present disclosure, an inflection point is a point on a lens surface with a curvature changing from positive to negative or from negative to positive.

According to the imaging system lens assembly of the present disclosure, the image surface of the imaging system lens assembly, based on the corresponding image sensor, can be planar or curved. In particular, the image surface can be a concave curved surface facing towards the object side. According to the imaging system lens assembly of the present disclosure, at least one image correcting element (such as a field flattener) can be selectively disposed between the lens element closest to the image side of the imaging system lens assembly and the image surface on an imaging optical path so as to correct the image (such as the field curvature). Properties of the image correcting element, such as curvature, thickness, refractive index, position, surface shape (convex/concave, spherical/aspheric, diffractive and Fresnel etc.) can be adjusted according to the requirements of the imaging apparatus. In general, the image correcting element is preferably a thin plano-concave element having a concave surface towards the object side and is disposed close to the image surface.

According to the imaging system lens assembly of the present disclosure, at least one element with light path folding function can be selectively disposed between the imaged object and the image surface, such as a prism or a mirror. Therefore, it is favorable for providing high flexible space arrangement of the imaging system lens assembly, so that the compactness of the electronic device would not be restricted by the optical total track length of the imaging system lens assembly. FIG. 24A is a schematic view of an arrangement of a light path folding element LF in the imaging system lens assembly of the present disclosure. FIG. 24B is a schematic view of another arrangement of the light path folding element LF in the imaging system lens assembly of the present disclosure. As shown in FIG. 24A and FIG. 24B, the imaging system lens assembly includes, in order from an imaged object (not shown in drawings) to an image surface IMG, a first optical axis OA1, the light path folding element LF and a second optical axis OA2, wherein the light path folding element LF can be disposed between the imaged object and a lens group LG of the imaging system lens assembly. The imaging system lens assembly can include a light filter FL disposed between the lens group LG and the image surface IMG, and the plane of incidence and the exit plane of the light path folding element LF can be planar as shown in FIG. 24A or be curved as shown in FIG. 24B. Moreover, FIG. 24C is a schematic view of an arrangement of two light path folding elements LF1, LF2 in the imaging system lens assembly of the present disclosure. FIG. 24D is a schematic view of another arrangement of the two light path folding elements LF1, LF2 in the imaging system lens assembly of the present disclosure. As shown in FIG. 24C and FIG. 24D, the imaging system lens assembly includes, in order from an imaged object (not shown in drawings) to an image surface IMG, a first optical axis OA1, the light path folding element LF1, a second optical axis OA2, the light path folding element LF2 and a third optical axis OA3, wherein the light path folding element LF1 is disposed between the imaged object and a lens group LG of the imaging system lens assembly, and the light path folding element LF2 is disposed between the lens group LG of the imaging system lens assembly and the image surface IMG. The imaging system lens assembly can include a light filter FL disposed between the lens group LG and the light path folding element LF2, and the light path folding element LF2 can be a prism as shown in FIG. 24C or a mirror as shown in FIG. 24D. Furthermore, FIG. 24E is a schematic view of one another arrangement of the light path folding element LF in the imaging system lens assembly of the present disclosure. As shown in FIG. 24E, the imaging system lens assembly includes, in order from an imaged object (not shown in drawings) to an image surface IMG, a first optical axis OA1, the light path folding element LF, a second optical axis OA2 and a third optical axis OA3, wherein the light path folding element LF is disposed between a lens group LG of the imaging system lens assembly and the image surface IMG. The imaging system lens assembly can include a light filter FL disposed between the lens group LG and the light path folding element LF, and the light path can be folded twice in the light path folding element LF as shown in FIG. 24E. The imaging system lens assembly can also be selectively disposed with three or more light path folding elements, the type, amount and location of the light path folding elements will not be limited to the present disclosure.

According to the imaging system lens assembly of the present disclosure, the imaging system lens assembly can include at least one stop, such as an aperture stop, a glare stop or a field stop. Said glare stop or said field stop is for eliminating the stray light and thereby improving the image resolution thereof.

According to the imaging system lens assembly of the present disclosure, an aperture stop can be configured as a front stop or a middle stop. A front stop disposed between the imaged object and the first lens element can provide a longer distance between an exit pupil of the imaging system lens assembly and the image surface, and thereby obtains a telecentric effect and improves the image-sensing efficiency of the image sensor, such as CCD or CMOS. A middle stop disposed between the first lens element and the image surface is favorable for enlarging the field of view of the imaging system lens assembly and thereby provides a wide field of view for the same.

According to the imaging system lens assembly of the present disclosure, an aperture adjusting unit can be properly configured. The aperture adjusting unit can be a mechanical part or a light control part, and the dimension and the shape of the aperture adjusting unit can be electrically controlled. The mechanical part can include a moveable component such as a blade group or a shielding plate. The light control part can include a screen component such as a light filter, electrochromic material, a liquid crystal layer or the like. The amount of incoming light or the exposure time of the image can be controlled by the aperture adjusting unit to enhance the image moderation ability. In addition, the aperture adjusting unit can be the aperture stop of the imaging system lens assembly according to the present disclosure, so as to moderate the image properties such as depth of field or the exposure speed by changing f-number.

According to the imaging system lens assembly of the present disclosure, one or more optical element can be properly configured, so as to limit the way of light passing through the imaging system lens assembly. The aforementioned optical element can be a filter, a polarizer, etc., and it is not limited thereto. Moreover, the aforementioned optical element can be a single piece of element, a complex assembly or presented in a form of membrane, which is not limited thereto. The aforementioned optical element can be disposed at the object side, at the image side or between the lens elements of the imaging system lens assembly, so as to allow the specific light to pass through, which will meet the requirements of applications.

According to the imaging system lens assembly of the present disclosure, the imaging system lens assembly can be utilized in 3D (three-dimensional) image capturing applications, in products such as digital cameras, mobile devices, digital tablets, smart TVs, surveillance systems, motion sensing input devices, driving recording systems, rearview camera systems, wearable devices, and unmanned aerial vehicles.

According to the present disclosure, an imaging apparatus is provided. The imaging apparatus includes the aforementioned imaging system lens assembly and an image sensor, wherein the image sensor is disposed on the image surface of the aforementioned imaging system lens assembly. Through arranging the refractive power and the surface shape of the second lens element, as well as the surface shape of the third lens element and the arrangement of the lens elements and the back focal length of the imaging system lens assembly, it is favorable for correcting the aberrations, controlling the light path and ensuring that the imaging system lens assembly can perform better telephoto ability, so as to enhance the image quality. Moreover, the imaging apparatus can further include a barrel member, a holder member or a combination thereof.

According to the present disclosure, an electronic device is provided, wherein the electronic device includes the aforementioned imaging apparatus. Therefore, it is favorable for enhancing the image quality. Moreover, the electronic device can further include, but not limited to, a control unit, a display, a storage unit, a random access memory unit (RAM) or a combination thereof.

According to the above description of the present disclosure, the following specific embodiments are provided for further explanation.

1st Embodiment

FIG. 1 is a schematic view of an imaging apparatus 1 according to the 1st embodiment of the present disclosure. FIG. 2 shows, in order from left to right, spherical aberration curves, astigmatic field curves and a distortion curve of the imaging apparatus 1 according to the 1st embodiment. In FIG. 1 , the imaging apparatus 1 according to the 1st embodiment includes an imaging system lens assembly (its reference number is omitted) and an image sensor IS. The imaging system lens assembly includes, in order from an object side to an image side along an optical path, an aperture stop ST, a first lens element E1, a second lens element E2, a third lens element E3, a stop S1, a fourth lens element E4, a filter E5 and an image surface IMG, wherein the image sensor IS is disposed on the image surface IMG of the imaging system lens assembly. The imaging system lens assembly includes four lens elements (E1, E2, E3, E4) without additional one or more lens elements inserted between the first lens element E1 and the fourth lens element E4, and there is an air gap between each of adjacent lens elements of the four lens elements of the imaging system lens assembly.

The first lens element E1 with positive refractive power has an object-side surface being convex in a paraxial region thereof and an image-side surface being concave in a paraxial region thereof. The first lens element E1 is made of plastic material, and has the object-side surface and the image-side surface being both aspheric. Moreover, the object-side surface of the first lens element E1 includes one inflection point, and the image-side surface of the first lens element E1 includes one inflection point.

The second lens element E2 with negative refractive power has an object-side surface being concave in a paraxial region thereof and an image-side surface being concave in a paraxial region thereof. The second lens element E2 is made of plastic material, and has the object-side surface and the image-side surface being both aspheric. Moreover, the object-side surface of the second lens element E2 includes one inflection point.

The third lens element E3 with negative refractive power has an object-side surface being convex in a paraxial region thereof and an image-side surface being concave in a paraxial region thereof. The third lens element E3 is made of plastic material, and has the object-side surface and the image-side surface being both aspheric. Moreover, the object-side surface of the third lens element E3 includes two inflection points, and the image-side surface of the third lens element E3 includes two inflection points.

The fourth lens element E4 with positive refractive power has an object-side surface being convex in a paraxial region thereof and an image-side surface being concave in a paraxial region thereof. The fourth lens element E4 is made of plastic material, and has the object-side surface and the image-side surface being both aspheric. Moreover, the object-side surface of the fourth lens element E4 includes two inflection points, and the image-side surface of the fourth lens element E4 includes one inflection point.

The filter E5 is made of glass material and disposed between the fourth lens element E4 and the image surface IMG and will not affect a focal length of the imaging system lens assembly.

The equation of the aspheric surface profiles of the aforementioned lens elements is expressed as follows:

${{X(Y)} = {{\left( {Y^{2}/R} \right)/\left( {1 + {{sqrt}\left( {1 - {\left( {1 + k} \right) \times \left( {Y/R} \right)^{2}}} \right)}} \right)} + {\sum\limits_{i}{\left( {Ai} \right) \times \left( Y^{i} \right)}}}};$

wherein,

-   -   X is a displacement in parallel with an optical axis from the         intersection point of the aspheric surface and the optical axis         to a point at a distance Y from the optical axis on the aspheric         surface;     -   Y is the vertical distance from the point on the aspheric         surface to the optical axis;     -   R is the curvature radius;     -   k is the conic coefficient; and     -   Ai is the i-th aspheric coefficient.

In the imaging system lens assembly according to the 1st embodiment, when a focal length of the imaging system lens assembly is f, an f-number of the imaging system lens assembly is Fno, and half of a maximum field of view of the imaging system lens assembly is HFOV, these parameters have the following values: f=18.32 mm; Fno=3.51; and HFOV=10.1 degrees.

In the imaging system lens assembly according to the 1st embodiment, when a curvature radius of the object-side surface of the first lens element E1 is R1, a curvature radius of the image-side surface of the first lens element E1 is R2, a curvature radius of the object-side surface of the second lens element E2 is R3, and a curvature radius of the image-side surface of the second lens element E2 is R4, the following conditions are satisfied: (R3+R4)/(R3−R4)=−0.78; and |R1/R21=0.08.

In the imaging system lens assembly according to the 1st embodiment, when the focal length of the imaging system lens assembly is f, a focal length of the first lens element E1 is f1, a focal length of the second lens element E2 is f2, a focal length of the third lens element E3 is f3, and a focal length of the fourth lens element E4 is f4, the following conditions are satisfied: |f1/f3|+|f1/f4|=0.75; |f1/f4|=0.59; |f2/f41=0.58; and f/f2=−2.15.

In the imaging system lens assembly according to the 1st embodiment, when an axial distance between the aperture stop ST and the image-side surface of the fourth lens element E4 is SD, an axial distance between the object-side surface of the first lens element E1 and the image-side surface of the fourth lens element E4 is TD, and an axial distance between the image-side surface of the fourth lens element E4 and the image surface IMG is BL, the following conditions are satisfied: SD/TD=0.88; and TD/BL=0.53.

In the imaging system lens assembly according to the 1st embodiment, when an axial distance between the first lens element E1 and the second lens element E2 is T12, an axial distance between the second lens element E2 and the third lens element E3 is T23, an axial distance between the third lens element E3 and the fourth lens element E4 is T34, a sum of all axial distances between adjacent lens elements of the imaging system lens assembly is ΣAT, a central thickness of the first lens element E1 is CT1, a central thickness of the second lens element E2 is CT2, a central thickness of the third lens element E3 is CT3, a central thickness of the fourth lens element E4 is CT4, and a sum of all central thicknesses of the four lens elements of the imaging system lens assembly is ΣCT, the following conditions are satisfied: ΣAT/ΣCT=0.61; T23/T12=4.30; CT3/CT1=0.34; CT4/CT1=0.41; CT4/CT2=0.57; and (CT3+CT4)/CT1=0.76; according to the 1st embodiment, the axial distance between adjacent lens elements is the distance along the optical axis between two adjacent lens surfaces of the two adjacent lens elements; ΣAT=T12+T23+T34; ΣCT=CT1+CT2+CT3+CT4.

In the imaging system lens assembly according to the 1st embodiment, when the focal length of the second lens element E2 is f2, and the central thickness of the second lens element E2 is CT2, the following condition is satisfied: f2/CT2=−7.45.

In the imaging system lens assembly according to the 1st embodiment, when an Abbe number of the second lens element E2 is V2, and an Abbe number of the fourth lens element E4 is V4, the following condition is satisfied: V4/V2=1.11.

In the imaging system lens assembly according to the 1st embodiment, when a height of a maximum effective radius of the object-side surface of the first lens element E1 is Y1R1, and a height of a maximum effective radius of the image-side surface of the fourth lens element E4 is Y4R2, the following condition is satisfied: Y1R1/Y4R2=1.27.

The detailed optical data of the 1st embodiment are shown in Table 1A and the aspheric surface data are shown in Table 1B below.

TABLE 1A 1st Embodiment f = 18.32 mm, Fno = 3.51, HFOV = 10.1 deg. Focal Surface # Curvature Radius Thickness Material Index Abbe # Length 0 Object Plano Infinity 1 Ape. Stop Plano −0.747 2 Lens 1 4.3884 ASP 1.583 Plastic 1.545 56.1 8.62 3 57.8666 ASP 0.398 4 Lens 2 −5.9346 ASP 1.144 Plastic 1.614 25.6 −8.52 5 47.6190 ASP 1.710 6 Lens 3 2.3178 ASP 0.546 Plastic 1.660 20.4 −52.24 7 1.9684 ASP 0.469 8 Stop Plano −0.168 9 Lens 4 3.8882 ASP 0.650 Plastic 1.587 28.3 14.72 10 6.6288 ASP 6.411 11 Filter Plano 0.210 Glass 1.517 64.2 — 12 Plano 5.250 13 Image Plano — Reference wavelength is 587.6 nm (d-line). Effective radius of Surface 8 (Stop S1) is 2.04 mm.

TABLE 1B Aspheric Coefficients Surface # 2 3 4 5 k= −3.03236000E−01  7.15903000E+01 −1.37110000E+01  9.90000000E+01 A4=  8.07909950E−04  5.14874950E−03  4.08492990E−03 −1.10801850E−03 A6= −1.72831050E−04 −1.83321470E−03 −9.70978130E−04  2.04942200E−03 A8=  3.93007820E−05  6.76996880E−04  6.75561570E−04 −6.85957000E−04 A10= −9.44110080E−06 −1.45017350E−04 −1.97323110E−04  2.11700370E−04 A12=  6.36953450E−07  1.33848440E−05  3.09467880E−05 −4.45430340E−05 A14= −6.68844540E−08 −5.62588530E−07 −2.54122720E−06  5.90064860E−06 A16=  8.40301270E−09  8.41540270E−08 −3.33114150E−07 Surface # 6 7 9 10 k= −5.23153000E+00 −5.58824000E+00  1.75261000E+00  5.59218000E+00 A4= −2.35733760E−03 −1.77602260E−02 −5.47553300E−02 −1.27333660E−02 A6= −7.17259740E−04  5.46986750E−03  2.09586040E−02  4.50080920E−03 A8= −1.75366030E−04 −3.24198230E−03 −9.37611390E−03 −1.43893130E−03 A10=  1.72465500E−04  1.54870650E−03  3.42369920E−03  2.90891370E−04 A12= −6.93992390E−05 −4.78521660E−04 −9.05406970E−04 −5.58344870E−05 A14=  1.45031670E−05  8.00783890E−05  1.36208630E−04  7.10991410E−06 A16= −1.06448060E−06 −5.19438470E−06 −8.56857140E−06 −4.11385200E−07

Table 1A shows the detailed optical data of FIG. 1 of the 1st embodiment, wherein the curvature radius, thickness and the focal length are shown in millimeters (mm), Surface numbers 0-13 represent the surfaces sequentially arranged from the object side to the image side, and the refractive index is measured in accordance with the reference wavelength. Table 1B shows the aspheric surface data of the 1st embodiment, wherein k represents the conic coefficient of the equation of the aspheric surface profiles, and A4-A16 represent the aspheric coefficients of each surface ranging from the 4th order to the 16th order. The tables presented below for each embodiment correspond to the schematic view and aberration curves of each embodiment, and term definitions of the tables are the same as those in Table 1A and Table 1B of the 1st embodiment. Therefore, an explanation in this regard will not be provided again.

2nd Embodiment

FIG. 3 is a schematic view of an imaging apparatus 2 according to the 2nd embodiment of the present disclosure. FIG. 4 shows, in order from left to right, spherical aberration curves, astigmatic field curves and a distortion curve of the imaging apparatus 2 according to the 2nd embodiment. In FIG. 3 , the imaging apparatus 2 according to the 2nd embodiment includes an imaging system lens assembly (its reference number is omitted) and an image sensor IS. The imaging system lens assembly includes, in order from an object side to an image side along an optical path, an aperture stop ST, a first lens element E1, a second lens element E2, a third lens element E3, a stop S1, a fourth lens element E4, a filter E5 and an image surface IMG, wherein the image sensor IS is disposed on the image surface IMG of the imaging system lens assembly. The imaging system lens assembly includes four lens elements (E1, E2, E3, E4) without additional one or more lens elements inserted between the first lens element E1 and the fourth lens element E4, and there is an air gap between each of adjacent lens elements of the four lens elements of the imaging system lens assembly.

The first lens element E1 with positive refractive power has an object-side surface being convex in a paraxial region thereof and an image-side surface being convex in a paraxial region thereof. The first lens element E1 is made of plastic material, and has the object-side surface and the image-side surface being both aspheric. Moreover, the object-side surface of the first lens element E1 includes one inflection point, and the image-side surface of the first lens element E1 includes two inflection points.

The second lens element E2 with negative refractive power has an object-side surface being concave in a paraxial region thereof and an image-side surface being convex in a paraxial region thereof. The second lens element E2 is made of plastic material, and has the object-side surface and the image-side surface being both aspheric. Moreover, the object-side surface of the second lens element E2 includes one inflection point, and the image-side surface of the second lens element E2 includes one inflection point.

The third lens element E3 with positive refractive power has an object-side surface being convex in a paraxial region thereof and an image-side surface being concave in a paraxial region thereof. The third lens element E3 is made of plastic material, and has the object-side surface and the image-side surface being both aspheric. Moreover, the object-side surface of the third lens element E3 includes one inflection point, and the image-side surface of the third lens element E3 includes two inflection points.

The fourth lens element E4 with positive refractive power has an object-side surface being concave in a paraxial region thereof and an image-side surface being convex in a paraxial region thereof. The fourth lens element E4 is made of glass material, and has the object-side surface and the image-side surface being both aspheric.

The filter E5 is made of glass material and disposed between the fourth lens element E4 and the image surface IMG and will not affect a focal length of the imaging system lens assembly.

The detailed optical data of the 2nd embodiment are shown in Table 2A and the aspheric surface data are shown in Table 2B below.

TABLE 2A 2nd Embodiment f = 17.66 mm, Fno = 3.37, HFOV = 10.5 deg. Focal Surface # Curvature Radius Thickness Material Index Abbe # Length 0 Object Plano Infinity 1 Ape. Stop Plano −0.762 2 Lens 1 4.4146 ASP 1.714 Plastic 1.534 56.0 7.51 3 −38.0958 ASP 0.514 4 Lens 2 −3.0090 ASP 1.294 Plastic 1.587 28.3 −6.25 5 −19.3258 ASP 0.804 6 Lens 3 2.8399 ASP 1.072 Plastic 1.587 28.3 21.33 7 3.1598 ASP 0.347 8 Stop Plano 0.371 9 Lens 4 −33.3333 ASP 0.650 Glass 1.548 45.9 40.67 10 −13.4496 ASP 6.411 11 Filter Plano 0.210 Glass 1.517 64.2 — 12 Plano 5.017 13 Image Plano — Reference wavelength is 587.6 nm (d-line). Effective radius of Surface 8 (Stop S1) is 2.04 mm.

TABLE 2B Aspheric Coefficients Surface # 2 3 4 5 k= −3.56974000E−01 −3.03969000E+01 −9.12102000E+00 4.23414000E+01 A4=  1.06564930E−03  1.30285670E−02  8.33800530E−03 6.37593820E−03 A6= −2.40869450E−04 −4.35839510E−03 −3.42569440E−03 −2.28125470E−03  A8=  1.75971460E−05  9.93644120E−04  1.35500670E−03 1.29717550E−03 A10= −2.53083760E−06 −1.40956350E−04 −3.30352450E−04 −4.32966090E−04  A12= −5.23891600E−08  9.07206930E−06  4.88734070E−05 8.02427450E−05 A14= −2.98868030E−08 −2.96018780E−07 −4.12608730E−06 −7.56347250E−06  A16=  1.13766990E−08  1.52943270E−07 2.84113460E−07 Surface # 6 7 9 10 k= −6.84043000E+00 −8.83354000E+00 −9.90000000E+01 −1.08878000E+01  A4= −3.30277260E−03 −1.18269550E−02 −2.74914460E−02 −1.35894100E−02  A6= −5.42111410E−03 −5.02502070E−04  4.54625410E−03 1.94444870E−03 A8=  3.49785680E−03  2.49475550E−03  4.79340390E−04 2.89560460E−04 A10= −1.19681940E−03 −1.10956970E−03 −4.45088320E−04 −3.34108120E−04  A12=  2.11083560E−04  2.01650190E−04  4.22395420E−05 8.37830890E−05 A14= −1.74683050E−05 −1.35938480E−05  8.62207650E−06 −9.00932110E−06  A16=  4.83077690E−07  1.29483070E−07 −1.27906510E−06 3.23749790E−07

In the 2nd embodiment, the equation of the aspheric surface profiles of the aforementioned lens elements is the same as the equation of the 1st embodiment. Also, the definitions of these parameters shown in the following table are the same as those stated in the 1st embodiment with corresponding values for the 2nd embodiment, so an explanation in this regard will not be provided again.

Moreover, these parameters can be calculated from Table 2A and Table 2B as the following values and satisfy the following conditions:

2nd Embodiment f [mm] 17.66 TD/BL 0.58 Fno 3.37 ΣAT/ΣCT 0.43 HFOV [deg.] 10.5 T23/T12 1.56 (R3 + R4)/(R3 − R4) −1.37 CT3/CT1 0.63 |R1/R2| 0.12 CT4/CT1 0.38 |f1/f3| + |f1/f4| 0.54 CT4/CT2 0.50 |f1/f4| 0.18 (CT3 + CT4)/CT1 1.00 |f2/f4| 0.15 f2/CT2 −4.83 f/f2 −2.82 V4/V2 1.62 SD/TD 0.89 Y1R1/Y4R2 1.19

3rd Embodiment

FIG. 5 is a schematic view of an imaging apparatus 3 according to the 3rd embodiment of the present disclosure. FIG. 6 shows, in order from left to right, spherical aberration curves, astigmatic field curves and a distortion curve of the imaging apparatus 3 according to the 3rd embodiment. In FIG. 5 , the imaging apparatus 3 according to the 3rd embodiment includes an imaging system lens assembly (its reference number is omitted) and an image sensor IS. The imaging system lens assembly includes, in order from an object side to an image side along an optical path, an aperture stop ST, a first lens element E1, a second lens element E2, a third lens element E3, a stop S1, a fourth lens element E4, a filter E5 and an image surface IMG, wherein the image sensor IS is disposed on the image surface IMG of the imaging system lens assembly. The imaging system lens assembly includes four lens elements (E1, E2, E3, E4) without additional one or more lens elements inserted between the first lens element E1 and the fourth lens element E4, and there is an air gap between each of adjacent lens elements of the four lens elements of the imaging system lens assembly.

The first lens element E1 with positive refractive power has an object-side surface being convex in a paraxial region thereof and an image-side surface being convex in a paraxial region thereof. The first lens element E1 is made of plastic material, and has the object-side surface and the image-side surface being both aspheric. Moreover, the object-side surface of the first lens element E1 includes one inflection point.

The second lens element E2 with negative refractive power has an object-side surface being concave in a paraxial region thereof and an image-side surface being convex in a paraxial region thereof. The second lens element E2 is made of plastic material, and has the object-side surface and the image-side surface being both aspheric. Moreover, the object-side surface of the second lens element E2 includes one inflection point, and the image-side surface of the second lens element E2 includes one inflection point.

The third lens element E3 with positive refractive power has an object-side surface being convex in a paraxial region thereof and an image-side surface being concave in a paraxial region thereof. The third lens element E3 is made of plastic material, and has the object-side surface and the image-side surface being both aspheric. Moreover, the image-side surface of the third lens element E3 includes two inflection points.

The fourth lens element E4 with positive refractive power has an object-side surface being convex in a paraxial region thereof and an image-side surface being concave in a paraxial region thereof. The fourth lens element E4 is made of plastic material, and has the object-side surface and the image-side surface being both aspheric. Moreover, the object-side surface of the fourth lens element E4 includes one inflection point, and the image-side surface of the fourth lens element E4 includes one inflection point.

The filter E5 is made of glass material and disposed between the fourth lens element E4 and the image surface IMG and will not affect a focal length of the imaging system lens assembly.

The detailed optical data of the 3rd embodiment are shown in Table 3A and the aspheric surface data are shown in Table 3B below.

TABLE 3A 3rd Embodiment f = 18.29 mm, Fno = 3.51, HFOV = 10.1 deg. Focal Surface # Curvature Radius Thickness Material Index Abbe # Length 0 Object Plano Infinity 1 Ape. Stop Plano −0.596 2 Lens 1 5.1207 ASP 2.449 Plastic 1.545 56.1 7.46 3 −16.3961 ASP 0.371 4 Lens 2 −3.0134 ASP 1.292 Plastic 1.639 23.5 −6.00 5 −16.4461 ASP 0.522 6 Lens 3 2.9977 ASP 0.819 Plastic 1.660 20.4 21.71 7 3.3792 ASP 0.230 8 Stop Plano 0.018 9 Lens 4 5.1304 ASP 0.885 Plastic 1.614 25.6 45.22 10 5.8799 ASP 6.411 11 Filter Plano 0.210 Glass 1.517 64.2 — 12 Plano 5.207 13 Image Plano — Reference wavelength is 587.6 nm (d-line). Effective radius of Surface 8 (Stop S1) is 1.91 mm.

TABLE 3B Aspheric Coefficients Surface # 2 3 4 5 k= −7.58127000E−01  0.00000000E+00 −9.99334000E+00 −3.23040000E+01 A4=  1.73080900E−04  1.33997270E−02  9.72303960E−03  1.23411920E−02 A6= −1.37044620E−04 −5.43746460E−03 −3.63679780E−03 −4.01605460E−03 A8=  8.29759910E−06  1.62029120E−03  1.27762210E−03  9.78883520E−04 A10= −2.48775960E−06 −3.84718810E−04 −3.15989940E−04 −1.40289990E−04 A12=  1.04240820E−07  6.18888120E−05  5.25031240E−05  1.28413050E−05 A14= −5.75530710E−09 −5.85611180E−06 −5.11731840E−06 −6.33792730E−07 A16=  2.39209810E−07  2.13742740E−07  4.35866890E−09 Surface # 6 7 9 10 k= −5.22353000E+00 −1.42522000E+01  9.07520000E−01 −1.71743000E+00 A4= −1.44697410E−02 −3.43237290E−02 −6.00815080E−02 −1.15685880E−02 A6=  9.18799320E−03  2.11898510E−02  2.58959550E−02  3.27680790E−03 A8= −4.14342900E−03 −9.66549370E−03 −1.06471810E−02  1.40687750E−03 A10=  1.15628000E−03  2.70217120E−03  2.87438090E−03  4.26018840E−04 A12= −1.93548570E−04 −4.53234170E−04 −4.92292310E−04 −8.16689870E−05 A14=  1.90920890E−05  4.30874190E−05  4.92490990E−05  8.82115650E−06 A16= −8.13155460E−07 −1.66138490E−06 −2.18803280E−06 −4.12709010E−07

In the 3rd embodiment, the equation of the aspheric surface profiles of the aforementioned lens elements is the same as the equation of the 1st embodiment. Also, the definitions of these parameters shown in the following table are the same as those stated in the 1st embodiment with corresponding values for the 3rd embodiment, so an explanation in this regard will not be provided again.

Moreover, these parameters can be calculated from Table 3A and Table 3B as the following values and satisfy the following conditions:

3rd Embodiment f [mm] 18.29 TD/BL 0.56 Fno 3.51 ΣAT/ΣCT 0.21 HFOV [deg.] 10.1 T23/T12 1.41 (R3 + R4)/(R3 − R4) −1.45 CT3/CT1 0.33 |R1/R2| 0.31 CT4/CT1 0.36 |f1/f3| + |f1/f4| 0.51 CT4/CT2 0.68 |f1/f4| 0.16 (CT3 + CT4)/CT1 0.70 |f2/f4| 0.13 f2/CT2 −4.65 f/f2 −3.05 V4/V2 1.09 SD/TD 0.91 Y1R1/Y4R2 1.35

4th Embodiment

FIG. 7 is a schematic view of an imaging apparatus 4 according to the 4th embodiment of the present disclosure. FIG. 8 shows, in order from left to right, spherical aberration curves, astigmatic field curves and a distortion curve of the imaging apparatus 4 according to the 4th embodiment. In FIG. 7 , the imaging apparatus 4 according to the 4th embodiment includes an imaging system lens assembly (its reference number is omitted) and an image sensor IS. The imaging system lens assembly includes, in order from an object side to an image side along an optical path, an aperture stop ST, a first lens element E1, a second lens element E2, a third lens element E3, a stop S1, a fourth lens element E4, a filter E5 and an image surface IMG, wherein the image sensor IS is disposed on the image surface IMG of the imaging system lens assembly. The imaging system one or more lens elements inserted between the first lens element E1 and the fourth lens element E4, and there is an air gap between each of adjacent lens elements of the four lens elements of the imaging system lens assembly.

The first lens element E1 with positive refractive power has an object-side surface being convex in a paraxial region thereof and an image-side surface being concave in a paraxial region thereof. The first lens element E1 is made of plastic material, and has the object-side surface and the image-side surface being both aspheric. Moreover, the image-side surface of the first lens element E1 includes one inflection point.

The second lens element E2 with negative refractive power has an object-side surface being concave in a paraxial region thereof and an image-side surface being convex in a paraxial region thereof. The second lens element E2 is made of plastic material, and has the object-side surface and the image-side surface being both aspheric. Moreover, the object-side surface of the second lens element E2 includes two inflection points, and the image-side surface of the second lens element E2 includes two inflection points.

The third lens element E3 with negative refractive power has an object-side surface being convex in a paraxial region thereof and an image-side surface being concave in a paraxial region thereof. The third lens element E3 is made of plastic material, and has the object-side surface and the image-side surface being both aspheric. Moreover, the object-side surface of the third lens element E3 includes one inflection point, and the image-side surface of the third lens element E3 includes two inflection points.

The fourth lens element E4 with positive refractive power has an object-side surface being convex in a paraxial region thereof and an image-side surface being concave in a paraxial region thereof. The fourth lens element E4 is made of glass material, and has the object-side surface and the image-side surface being both aspheric. Moreover, the object-side surface of the fourth lens element E4 includes two inflection points, and the image-side surface of the fourth lens element E4 includes one inflection point.

The filter E5 is made of glass material and disposed between the fourth lens element E4 and the image surface IMG and will not affect a focal length of the imaging system lens assembly.

The detailed optical data of the 4th embodiment are shown in Table 4A and the aspheric surface data are shown in Table 4B below.

TABLE 4A 4th Embodiment f = 18.30 mm, Fno = 3.51, HFOV = 10.1 deg. Focal Surface # Curvature Radius Thickness Material Index Abbe # Length 0 Object Plano Infinity 1 Ape. Stop Plano −0.837 2 Lens 1 4.6972 ASP 1.523 Plastic 1.545 56.1 10.38 3 24.5817 ASP 1.130 4 Lens 2 −4.0388 ASP 1.224 Plastic 1.639 23.5 −9.72 5 −12.9312 ASP 1.545 6 Lens 3 2.7131 ASP 0.650 Plastic 1.639 23.5 −53.88 7 2.2800 ASP 0.454 8 Stop Plano −0.145 9 Lens 4 3.8546 ASP 0.689 Glass 1.620 36.3 12.77 10 6.9965 ASP 6.411 11 Filter Plano 0.210 Glass 1.517 64.2 — 12 Plano 5.383 13 Image Plano — Reference wavelength is 587.6 nm (d-line). Effective radius of Surface 8 (Stop S1) is 2.04 mm.

TABLE 4B Aspheric Coefficients Surface # 2 3 4 5 k= 2.85581400E−01 −9.75080300E+01 −7.12446500E+00 2.36208800E+01 A4= 5.43918937E−04  4.92337744E−03  3.72488617E−03 3.45405870E−03 A6= 1.17524302E−04  1.02310006E−04  9.26455501E−04 2.21349414E−03 A8= −5.21537946E−05  −2.12221262E−04 −1.56697614E−03 −1.89744511E−03  A10= 7.39203529E−06  2.20201915E−05  7.33153579E−04 7.70542888E−04 A12= 3.26961486E−07  1.33890377E−05 −1.60913663E−04 −1.58625142E−04  A14= −8.41620196E−08  −2.98959287E−06  1.73911385E−05 1.63494038E−05 A16=  1.53756199E−07 −7.77119111E−07 −6.69291759E−07  Surface # 6 7 9 10 k= −5.27953700E+00  −6.65105800E+00  1.53956400E+00 3.35331000E+00 A4= −1.26720471E−02  −3.01639148E−02 −5.97724218E−02 −1.58302639E−02  A6= 8.09070339E−03  1.72487236E−02  1.81837608E−02 1.81771828E−03 A8= −3.46774076E−03  −5.22984942E−03 −2.75967062E−03 1.62317822E−03 A10= 7.85115453E−04  1.08975495E−03  3.22478179E−05 −1.18884402E−03  A12= −9.96227485E−05  −2.86507257E−04 −1.43759164E−04 3.04710760E−04 A14= 7.34347834E−06  5.86227076E−05  5.79926284E−05 −3.46856908E−05  A16= −3.08340060E−07  −4.56556126E−06 −5.53028947E−06 1.44835928E−06

In the 4th embodiment, the equation of the aspheric surface profiles of the aforementioned lens elements is the same as the equation of the 1st embodiment. Also, the definitions of these parameters shown in the following table are the same as those stated in the 1st embodiment with corresponding values for the 4th embodiment, so an explanation in this regard will not be provided again.

Moreover, these parameters can be calculated from Table 4A and Table 4B as the following values and satisfy the following conditions:

4th Embodiment f [mm] 18.30 TD/BL 0.59 Fno 3.51 ΣAT/ΣCT 0.73 HFOV [deg.] 10.1 T23/T12 1.37 (R3 + R4)/(R3 − R4) −1.91 CT3/CT1 0.43 |R1/R2| 0.19 CT4/CT1 0.45 |f1/f3| + |f1/f4| 1.00 CT4/CT2 0.56 |f1/f4| 0.81 (CT3 + CT4)/CT1 0.88 |f2/f4| 0.76 f2/CT2 −7.94 f/f2 −1.88 V4/V2 1.55 SD/TD 0.88 Y1R1/Y4R2 1.25

5th Embodiment

FIG. 9 is a schematic view of an imaging apparatus 5 according to the 5th embodiment of the present disclosure. FIG. 10 shows, in order from left to right, spherical aberration curves, astigmatic field curves and a distortion curve of the imaging apparatus 5 according to the 5th embodiment. In FIG. 9 , the imaging apparatus 5 according to the 5th embodiment includes an imaging system lens assembly (its reference number is omitted) and an image sensor IS. The imaging system lens assembly includes, in order from an object side to an image side along an optical path, an aperture stop ST, a first lens element E1, a second lens element E2, a third lens element E3, a stop S1, a fourth lens element E4, a filter E5 and an image surface IMG, wherein the image sensor IS is disposed on the image surface IMG of the imaging system lens assembly. The imaging system lens assembly includes four lens elements (E1, E2, E3, E4) without additional one or more lens elements inserted between the first lens element E1 and the fourth lens element E4, and there is an air gap between each of adjacent lens elements of the four lens elements of the imaging system lens assembly.

The first lens element E1 with positive refractive power has an object-side surface being convex in a paraxial region thereof and an image-side surface being convex in a paraxial region thereof. The first lens element E1 is made of plastic material, and has the object-side surface and the image-side surface being both aspheric. Moreover, the object-side surface of the first lens element E1 includes one inflection point, and the image-side surface of the first lens element E1 includes two inflection points.

The second lens element E2 with negative refractive power has an object-side surface being concave in a paraxial region thereof and an image-side surface being convex in a paraxial region thereof. The second lens element E2 is made of glass material, and has the object-side surface and the image-side surface being both aspheric. Moreover, the object-side surface of the second lens element E2 includes one inflection point, and the image-side surface of the second lens element E2 includes three inflection points.

The third lens element E3 with positive refractive power has an object-side surface being convex in a paraxial region thereof and an image-side surface being concave in a paraxial region thereof. The third lens element E3 is made of plastic material, and has the object-side surface and the image-side surface being both aspheric. Moreover, the object-side surface of the third lens element E3 includes two inflection points, and the image-side surface of the third lens element E3 includes one inflection point.

The fourth lens element E4 with positive refractive power has an object-side surface being concave in a paraxial region thereof and an image-side surface being convex in a paraxial region thereof. The fourth lens element E4 is made of plastic material, and has the object-side surface and the image-side surface being both aspheric.

The filter E5 is made of glass material and disposed between the fourth lens element E4 and the image surface IMG and will not affect a focal length of the imaging system lens assembly.

The detailed optical data of the 5th embodiment are shown in Table 5A and the aspheric surface data are shown in Table 5B below.

TABLE 5A 5th Embodiment f = 18.29 mm, Fno = 3.58, HFOV = 10.1 deg. Focal Surface # Curvature Radius Thickness Material Index Abbe # Length 0 Object Plano Infinity 1 Ape. Stop Plano −0.650 2 Lens 1 4.5759 ASP 1.579 Plastic 1.545 56.1 7.45 3 −31.6782 ASP 0.480 4 Lens 2 −3.0395 ASP 1.294 Glass 1.581 40.9 −6.29 5 −20.8124 ASP 0.736 6 Lens 3 2.6974 ASP 0.992 Plastic 1.545 56.1 17.07 7 3.3062 ASP 0.317 8 Stop Plano 0.457 9 Lens 4 −16.8798 ASP 0.873 Plastic 1.660 20.4 127.46 10 −14.3478 ASP 6.411 11 Filter Plano 0.210 Glass 1.517 64.2 — 12 Plano 5.711 13 Image Plano — Reference wavelength is 587.6 nm (d-line). Effective radius of Surface 8 (Stop S1) is 2.04 mm.

TABLE 5B Aspheric Coefficients Surface # 2 3 4 5 k= −5.82688000E−01  6.13246000E+01 −9.23614000E+00  4.97318000E+01 A4=  5.92090590E−04  1.12694130E−02  9.60874530E−03  8.58493640E−03 A6= −5.24572030E−05 −3.33323260E−03 −3.50291210E−03 −8.98747460E−04 A8= −5.72873390E−05  6.47559580E−04  1.04377210E−03 −5.43916210E−04 A10=  1.52125220E−05 −7.56310610E−05 −2.24450760E−04  2.35413270E−04 A12= −2.39342910E−06  2.50283210E−06  3.48648980E−05 −3.92985530E−05 A14=  7.94297320E−08 −1.43858820E−07 −3.55783350E−06  3.22125250E−06 A16=  3.35455490E−08  1.75363960E−07 −1.02921310E−07 Surface # 6 7 9 10 k= −5.42758000E+00 −1.09571000E+01 −1.68855000E+01 −9.90000000E+01 A4= −1.27967730E−02 −2.83455880E−02 −4.05850380E−02 −2.09323390E−02 A6=  6.08718670E−03  1.63251440E−02  1.50955310E−02  7.17505390E−03 A8= −1.52174250E−03 −5.79688380E−03 −4.24866160E−03 −2.08433590E−03 A10= −8.89320590E−05  1.22399890E−03  6.72925410E−04  3.69176950E−04 A12=  1.14934570E−04 −1.63400310E−04 −6.13713810E−05 −3.54744310E−05 A14= −2.09391920E−05  1.55510010E−05  4.46484620E−06  1.01165740E−06 A16=  1.32911070E−06 −9.50023250E−07 −5.02026930E−07  4.84131970E−08

In the 5th embodiment, the equation of the aspheric surface profiles of the aforementioned lens elements is the same as the equation of the 1st embodiment. Also, the definitions of these parameters shown in the following table are the same as those stated in the 1st embodiment with corresponding values for the 5th embodiment, so an explanation in this regard will not be provided again.

Moreover, these parameters can be calculated from Table 5A and Table 5B as the following values and satisfy the following conditions:

5th Embodiment f [mm] 18.29 TD/BL 0.55 Fno 3.58 ΣAT/ΣCT 0.42 HFOV [deg.] 10.1 T23/T12 1.53 (R3 + R4)/(R3 − R4) −1.34 CT3/CT1 0.63 |R1/R2| 0.14 CT4/CT1 0.55 |f1/f3| + |f1/f4| 0.49 CT4/CT2 0.67 |f1/f4| 0.06 (CT3 + CT4)/CT1 1.18 |f2/f4| 0.05 f2/CT2 −4.86 f/f2 −2.91 V4/V2 0.50 SD/TD 0.90 Y1R1/Y4R2 1.13

6th Embodiment

FIG. 11 is a schematic view of an imaging apparatus 6 according to the 6th embodiment of the present disclosure. FIG. 12 shows, in order from left to right, spherical aberration curves, astigmatic field curves and a distortion curve of the imaging apparatus 6 according to the 6th embodiment. In FIG. 11 , the imaging apparatus 6 according to the 6th embodiment includes an imaging system lens assembly (its reference number is omitted) and an image sensor IS. The imaging system lens assembly includes, in order from an object side to an image side along an optical path, a first lens element E1, an aperture stop ST, a second lens element E2, a third lens element E3, a fourth lens element E4, a filter E5 and an image surface IMG, wherein the image sensor IS is disposed on the image surface IMG of the imaging system lens assembly. The imaging system lens assembly includes four lens elements (E1, E2, E3, E4) without additional one or more lens elements inserted between the first lens element E1 and the fourth lens element E4, and there is an air gap between each of adjacent lens elements of the four lens elements of the imaging system lens assembly.

The first lens element E1 with positive refractive power has an object-side surface being convex in a paraxial region thereof and an image-side surface being convex in a paraxial region thereof. The first lens element E1 is made of plastic material, and has the object-side surface and the image-side surface being both aspheric. Moreover, the object-side surface of the first lens element E1 includes one inflection point, and the image-side surface of the first lens element E1 includes two inflection points.

The second lens element E2 with negative refractive power has an object-side surface being concave in a paraxial region thereof and an image-side surface being concave in a paraxial region thereof. The second lens element E2 is made of plastic material, and has the object-side surface and the image-side surface being both aspheric. Moreover, the object-side surface of the second lens element E2 includes two inflection points, and the image-side surface of the second lens element E2 includes one inflection point.

The third lens element E3 with positive refractive power has an object-side surface being convex in a paraxial region thereof and an image-side surface being concave in a paraxial region thereof. The third lens element E3 is made of plastic material, and has the object-side surface and the image-side surface being both aspheric. Moreover, the image-side surface of the third lens element E3 includes two inflection points.

The fourth lens element E4 with positive refractive power has an object-side surface being convex in a paraxial region thereof and an image-side surface being concave in a paraxial region thereof. The fourth lens element E4 is made of plastic material, and has the object-side surface and the image-side surface being both aspheric. Moreover, the object-side surface of the fourth lens element E4 includes one inflection point, and the image-side surface of the fourth lens element E4 includes one inflection point.

The filter E5 is made of glass material and disposed between the fourth lens element E4 and the image surface IMG and will not affect a focal length of the imaging system lens assembly.

The detailed optical data of the 6th embodiment are shown in Table 6A and the aspheric surface data are shown in Table 6B below.

TABLE 6A 6th Embodiment f = 15.22 mm, Fno = 3.00, HFOV = 12.0 deg. Focal Surface # Curvature Radius Thickness Material Index Abbe # Length 0 Object Plano Infinity 1 Lens 1 4.1621 ASP 2.200 Plastic 1.545 56.1 6.65 2 −22.7067 ASP 0.261 3 Ape. Stop Plano 0.383 4 Lens 2 −3.0055 ASP 1.036 Plastic 1.653 21.0 −3.88 5 18.2063 ASP 0.267 6 Lens 3 3.2907 ASP 0.678 Plastic 1.710 15.5 12.64 7 4.7509 ASP 0.347 8 Lens 4 4.1986 ASP 0.976 Plastic 1.614 26.0 16.91 9 6.4267 ASP 6.411 10 Filter Plano 0.210 Glass 1.517 64.2 — 11 Plano 2.498 12 Image Plano — Reference wavelength is 587.6 nm (d-line).

TABLE 6B Aspheric Coefficients Surface # 1 2 4 5 k= −1.14459000E−01 0.00000000E+00 −1.02142000E+01 −9.79783000E+01 A4=  3.93884550E−05 8.62292940E−03  1.20089310E−02  7.93406150E−03 A6= −1.01106060E−05 −1.20552110E−03  −2.92411030E−03 −2.57177720E−03 A8=  2.15774120E−06 1.04467340E−04  4.49494920E−04 −3.09113920E−05 A10= −2.96213850E−06 −1.52334300E−05  −2.28194980E−05  1.78253470E−04 A12=  4.11395360E−07 3.71215700E−06 −3.49512390E−06 −4.94608660E−05 A14= −3.28295820E−08 −7.51693730E−07   2.43542690E−07  5.61848500E−06 A16= 5.12278240E−08  1.65916260E−08 −2.40577880E−07 Surface # 6 7 8 9 k= −8.26516000E+00 −1.79269000E+01  −3.91306000E−01 −2.09956000E+00 A4= −1.71295330E−02 −3.44222360E−02  −5.20145420E−02 −1.70525870E−02 A6=  7.09096350E−03 1.64034020E−02  1.07749260E−02  3.72784490E−04 A8= −1.99178610E−03 −4.58399670E−03  −1.86458830E−03  2.64355200E−04 A10=  3.09992950E−04 6.09460390E−04 −3.72940530E−04 −1.97312610E−04 A12= −2.03062110E−05 1.58502440E−05  2.14467290E−04  6.20296570E−05 A14=  2.15727900E−06 −1.18895280E−05  −3.27647310E−05 −8.99992990E−06 A16= −2.96289490E−07 1.13551400E−06  1.67714060E−06  4.81710170E−07

In the 6th embodiment, the equation of the aspheric surface profiles of the aforementioned lens elements is the same as the equation of the 1st embodiment. Also, the definitions of these parameters shown in the following table are the same as those stated in the 1st embodiment with corresponding values for the 6th embodiment, so an explanation in this regard will not be provided again.

Moreover, these parameters can be calculated from Table 6A and Table 6B as the following values and satisfy the following conditions:

6th Embodiment f [mm] 15.22 TD/BL 0.67 Fno 3.00 ΣAT/ΣCT 0.26 HFOV [deg.] 12.0 T23/T12 0.41 (R3 + R4)/(R3 − R4) −0.72 CT3/CT1 0.31 |R1/R2| 0.18 CT4/CT1 0.44 |f1/f3| + |f1/f4| 0.92 CT4/CT2 0.94 |f1/f4| 0.39 (CT3 + CT4)/CT1 0.75 |f2/f4| 0.23 f2/CT2 −3.74 f/f2 −3.93 V4/V2 1.24 SD/TD 0.60 Y1R1/Y4R2 1.24

7th Embodiment

FIG. 13 is a schematic view of an imaging apparatus 7 according to the 7th embodiment of the present disclosure. FIG. 14 shows, in order from left to right, spherical aberration curves, astigmatic field curves and a distortion curve of the imaging apparatus 7 according to the 7th embodiment. In FIG. 13 , the imaging apparatus 7 according to the 7th embodiment includes an imaging system lens assembly (its reference number is omitted) and an image sensor IS. The imaging system lens assembly includes, in order from an object side to an image side along an optical path, an aperture stop ST, a first lens element E1, a second lens element E2, a third lens element E3, a stop S1, a fourth lens element E4, a filter E5 and an image surface IMG, wherein the image sensor IS is disposed on the image surface IMG of the imaging system lens assembly. The imaging system one or more lens elements inserted between the first lens element E1 and the fourth lens element E4, and there is an air gap between each of adjacent lens elements of the four lens elements of the imaging system lens assembly.

The first lens element E1 with positive refractive power has an object-side surface being convex in a paraxial region thereof and an image-side surface being convex in a paraxial region thereof. The first lens element E1 is made of plastic material, and has the object-side surface and the image-side surface being both aspheric. Moreover, the image-side surface of the first lens element E1 includes two inflection points.

The second lens element E2 with negative refractive power has an object-side surface being concave in a paraxial region thereof and an image-side surface being convex in a paraxial region thereof. The second lens element E2 is made of plastic material, and has the object-side surface and the image-side surface being both aspheric. Moreover, the object-side surface of the second lens element E2 includes two inflection points.

The third lens element E3 with positive refractive power has an object-side surface being convex in a paraxial region thereof and an image-side surface being concave in a paraxial region thereof. The third lens element E3 is made of plastic material, and has the object-side surface and the image-side surface being both aspheric.

The fourth lens element E4 with positive refractive power has an object-side surface being convex in a paraxial region thereof and an image-side surface being concave in a paraxial region thereof. The fourth lens element E4 is made of plastic material, and has the object-side surface and the image-side surface being both aspheric. Moreover, the object-side surface of the fourth lens element E4 includes two inflection points, and the image-side surface of the fourth lens element E4 includes one inflection point.

The filter E5 is made of glass material and disposed between the fourth lens element E4 and the image surface IMG and will not affect a focal length of the imaging system lens assembly.

The detailed optical data of the 7th embodiment are shown in Table 7A and the aspheric surface data are shown in Table 7B below.

TABLE 7A 7th Embodiment f = 18.25 mm, Fno = 3.50, HFOV = 10.1 deg. Focal Surface # Curvature Radius Thickness Material Index Abbe # Length 0 Object Plano Infinity 1 Ape. Stop Plano −0.725 2 Lens 1 4.8835 ASP 1.685 Plastic 1.545 56.1 8.35 3 −58.7888 ASP 0.900 4 Lens 2 −3.3754 ASP 1.312 Plastic 1.639 23.5 −6.48 5 −21.0376 ASP 0.696 6 Lens 3 3.6921 ASP 0.658 Plastic 1.660 20.4 31.33 7 4.1762 ASP 0.286 8 Stop Plano −0.092 9 Lens 4 4.6475 ASP 1.203 Plastic 1.587 28.3 24.45 10 6.2138 ASP 6.411 11 Filter Plano 0.210 Glass 1.517 64.2 — 12 Plano 5.221 13 Image Plano — Reference wavelength is 587.6 nm (d-line). Effective radius of Surface 8 (Stop S1) is 2.04 mm.

TABLE 7B Aspheric Coefficients Surface # 2 3 4 5 k=  2.88709000E−02 0.00000000E+00 −8.54342000E+00  5.03312000E+01 A4=  5.47329570E−04 6.92894830E−03  9.09524400E−03  9.74098670E−03 A6= −7.16762850E−05 −1.02553980E−03  −2.75571590E−03 −2.35570730E−03 A8=  1.02509070E−05 8.35776440E−05  4.76580330E−04 −1.43029640E−05 A10= −4.54265460E−06 −1.17182380E−05  −2.22622590E−05  1.85989040E−04 A12=  7.95917530E−07 4.44379110E−06 −4.56664420E−06 −4.82036780E−05 A14= −5.69065660E−08 −7.38023330E−07   6.33741570E−07  5.32128920E−06 A16= 3.52086860E−08 −2.68286790E−08 −2.31440960E−07 Surface # 6 7 9 10 k= −5.45453000E+00 −1.04991000E+01   2.76619000E+00  3.35843000E+00 A4= −1.46874500E−02 −3.31783500E−02  −4.18895140E−02 −8.50327880E−03 A6=  6.43093760E−03 1.73164420E−02  1.11375920E−02 −8.50240290E−04 A8= −1.92459740E−03 −4.82372070E−03  −2.07351210E−03  3.79951950E−04 A10=  3.35144410E−04 5.54836580E−04 −3.92900270E−04 −2.01711450E−04 A12= −2.41136410E−05 2.57127160E−05  2.18146110E−04  5.82526590E−05 A14=  1.19892780E−06 −8.38688430E−06  −3.18996250E−05 −8.35035590E−06 A16= −1.33671910E−07 3.65039000E−07  1.54760620E−06  4.62103500E−07

In the 7th embodiment, the equation of the aspheric surface profiles of the aforementioned lens elements is the same as the equation of the 1st embodiment. Also, the definitions of these parameters shown in the following table are the same as those stated in the 1st embodiment with corresponding values for the 7th embodiment, so an explanation in this regard will not be provided again.

Moreover, these parameters can be calculated from Table 7A and Table 7B as the following values and satisfy the following conditions:

7th Embodiment f [mm] 18.25 TD/BL 0.56 Fno 3.50 ΣAT/ΣCT 0.37 HFOV [deg.] 10.1 T23/T12 0.77 (R3 + R4)/(R3 − R4) −1.38 CT3/CT1 0.39 |R1/R2| 0.08 CT4/CT1 0.71 |f1/f3| + |f1/f4| 0.61 CT4/CT2 0.92 |f1/f4| 0.34 (CT3 + CT4)/CT1 1.10 |f2/f4| 0.27 f2/CT2 −4.94 f/f2 −2.82 V4/V2 1.20 SD/TD 0.89 Y1R1/Y4R2 1.24

8th Embodiment

FIG. 15 is a schematic view of an imaging apparatus 8 according to the 8th embodiment of the present disclosure. FIG. 16 shows, in order from left to right, spherical aberration curves, astigmatic field curves and a distortion curve of the imaging apparatus 8 according to the 8th embodiment. In FIG. 15 , the imaging apparatus 8 according to the 8th embodiment includes an imaging system lens assembly (its reference number is omitted) and an image sensor IS. The imaging system lens assembly includes, in order from an object side to an image side along an optical path, an aperture stop ST, a first lens element E1, a second lens element E2, a third lens element E3, a stop S1, a fourth lens element E4, a filter E5 and an image surface IMG, wherein the image sensor IS is disposed on the image surface IMG of the imaging system lens assembly. The imaging system lens assembly includes four lens elements (E1, E2, E3, E4) without additional one or more lens elements inserted between the first lens element E1 and the fourth lens element E4, and there is an air gap between each of adjacent lens elements of the four lens elements of the imaging system lens assembly.

The first lens element E1 with positive refractive power has an object-side surface being convex in a paraxial region thereof and an image-side surface being convex in a paraxial region thereof. The first lens element E1 is made of plastic material, and has the object-side surface and the image-side surface being both aspheric. Moreover, the object-side surface of the first lens element E1 includes one inflection point, and the image-side surface of the first lens element E1 includes two inflection points.

The second lens element E2 with negative refractive power has an object-side surface being concave in a paraxial region thereof and an image-side surface being convex in a paraxial region thereof. The second lens element E2 is made of plastic material, and has the object-side surface and the image-side surface being both aspheric. Moreover, the object-side surface of the second lens element E2 includes two inflection points.

The third lens element E3 with positive refractive power has an object-side surface being convex in a paraxial region thereof and an image-side surface being concave in a paraxial region thereof. The third lens element E3 is made of plastic material, and has the object-side surface and the image-side surface being both aspheric. Moreover, the image-side surface of the third lens element E3 includes two inflection points.

The fourth lens element E4 with negative refractive power has an object-side surface being concave in a paraxial region thereof and an image-side surface being convex in a paraxial region thereof. The fourth lens element E4 is made of plastic material, and has the object-side surface and the image-side surface being both aspheric.

The filter E5 is made of glass material and disposed between the fourth lens element E4 and the image surface IMG and will not affect a focal length of the imaging system lens assembly.

The detailed optical data of the 8th embodiment are shown in Table 8A and the aspheric surface data are shown in Table 8B below.

TABLE 8A 8th Embodiment f = 19.34 mm, Fno = 3.80, HFOV = 9.5 deg. Focal Surface # Curvature Radius Thickness Material Index Abbe # Length 0 Object Plano Infinity 1 Ape. Stop Plano −0.674 2 Lens 1 4.6575 ASP 2.200 Plastic 1.534 56.0 7.86 3 −35.9002 ASP 0.437 4 Lens 2 −3.0743 ASP 1.394 Plastic 1.669 19.5 −5.76 5 −17.9290 ASP 0.041 6 Lens 3 3.1643 ASP 0.853 Plastic 1.669 19.5 6.75 7 9.4178 ASP 0.104 8 Stop Plano 0.567 9 Lens 4 −5.2822 ASP 1.030 Plastic 1.614 25.6 −12.17 10 −19.3425 ASP 6.411 11 Filter Plano 0.210 Glass 1.517 64.2 — 12 Plano 5.848 13 Image Plano — Reference wavelength is 587.6 nm (d-line). Effective radius of Surface 8 (Stop S1) is 2.04 mm.

TABLE 8B Aspheric Coefficients Surface # 2 3 4 5 k= −4.80938000E−01  6.97476000E+01 −1.19706000E+01  4.96496000E+01 A4=  3.13598960E−04  1.67509730E−02  1.63142660E−02  1.26253110E−02 A6= −1.78923830E−04 −6.97715250E−03 −8.63439860E−03 −6.84836130E−03 A8= −3.35656240E−06  1.53237030E−03  2.89359990E−03  2.02430880E−03 A10=  3.76908340E−06 −2.13605280E−04 −6.27449360E−04 −2.53986320E−04 A12= −8.43260860E−07  2.49910940E−05  9.28275090E−05  2.36292820E−06 A14=  4.19136430E−08 −3.56764020E−06 −9.40585450E−06  1.56557230E−06 A16=  2.65375950E−07  4.73170030E−07 −3.36066800E−08 Surface # 6 7 9 10 k= −5.76419000E+00 −1.26903000E+01 −2.96435000E+01 −9.90000000E+01 A4= −1.40472480E−02 −1.98319470E−02 −3.01232100E−02 −5.02395490E−04 A6=  5.86790100E−03  1.01463240E−02  1.23976270E−02 −2.09006360E−04 A8= −2.38169280E−03 −4.60810930E−03 −6.12159030E−03  8.70395940E−05 A10=  4.93236040E−04  1.13534310E−03  2.08089280E−03 −3.93145910E−05 A12=  1.21697290E−05 −8.31203760E−05 −4.54562150E−04  8.64840350E−06 A14= −1.81470110E−05 −1.33184460E−05  5.60355220E−05 −9.14189440E−07 A16=  1.81901520E−06  1.98577870E−06 −3.03066170E−06  3.63887280E−08

In the 8th embodiment, the equation of the aspheric surface profiles of the aforementioned lens elements is the same as the equation of the 1st embodiment. Also, the definitions of these parameters shown in the following table are the same as those stated in the 1st embodiment with corresponding values for the 8th embodiment, so an explanation in this regard will not be provided again.

Moreover, these parameters can be calculated from Table 8A and Table 8B as the following values and satisfy the following conditions:

8th Embodiment f [mm] 19.35 TD/BL 0.53 Fno 3.80 ΣAT/ΣCT 0.21 HFOV [deg.] 9.5 T23/T12 0.09 (R3 + R4)/(R3 − R4) −1.41 CT3/CT1 0.39 |R1/R2| 0.13 CT4/CT1 0.47 |f1/f3| + |f1/f4| 1.81 CT4/CT2 0.74 |f1/f4| 0.65 (CT3 + CT4)/CT1 0.86 |f2/f4| 0.47 f2/CT2 −4.13 f/f2 −3.36 V4/V2 1.32 SD/TD 0.90 Y1R1/Y4R2 1.17

9th Embodiment

FIG. 17 is a schematic view of an imaging apparatus 9 according to the 9th embodiment of the present disclosure. FIG. 18 shows, in order from left to right, spherical aberration curves, astigmatic field curves and a distortion curve of the imaging apparatus 9 according to the 9th embodiment. In FIG. 17 , the imaging apparatus 9 according to the 9th embodiment includes an imaging system lens assembly (its reference number is omitted) and an image sensor IS. The imaging system lens assembly includes, in order from an object side to an image side along an optical path, an aperture stop ST, a first lens element E1, a second lens element E2, a third lens element E3, a stop S1, a fourth lens element E4, a filter E5 and an image surface IMG, wherein the image sensor IS is disposed on the image surface IMG of the imaging system lens assembly. The imaging system lens assembly includes four lens elements (E1, E2, E3, E4) without additional one or more lens elements inserted between the first lens element E1 and the fourth lens element E4, and there is an air gap between each of adjacent lens elements of the four lens elements of the imaging system lens assembly.

The first lens element E1 with positive refractive power has an object-side surface being convex in a paraxial region thereof and an image-side surface being concave in a paraxial region thereof. The first lens element E1 is made of plastic material, and has the object-side surface and the image-side surface being both aspheric.

The second lens element E2 with negative refractive power has an object-side surface being concave in a paraxial region thereof and an image-side surface being convex in a paraxial region thereof. The second lens element E2 is made of plastic material, and has the object-side surface and the image-side surface being both aspheric. Moreover, the object-side surface of the second lens element E2 includes one inflection point, and the image-side surface of the second lens element E2 includes one inflection point.

The third lens element E3 with positive refractive power has an object-side surface being convex in a paraxial region thereof and an image-side surface being concave in a paraxial region thereof. The third lens element E3 is made of plastic material, and has the object-side surface and the image-side surface being both aspheric. Moreover, the object-side surface of the third lens element E3 includes two inflection points, and the image-side surface of the third lens element E3 includes two inflection points.

The fourth lens element E4 with positive refractive power has an object-side surface being convex in a paraxial region thereof and an image-side surface being concave in a paraxial region thereof. The fourth lens element E4 is made of plastic material, and has the object-side surface and the image-side surface being both aspheric. Moreover, the object-side surface of the fourth lens element E4 includes two inflection points, and the image-side surface of the fourth lens element E4 includes one inflection point.

The filter E5 is made of glass material and disposed between the fourth lens element E4 and the image surface IMG and will not affect a focal length of the imaging system lens assembly.

The detailed optical data of the 9th embodiment are shown in Table 9A and the aspheric surface data are shown in Table 9B below.

TABLE 9A 9th Embodiment f = 12.26 mm, Fno = 3.15, HFOV = 15.0 deg. Focal Surface # Curvature Radius Thickness Material Index Abbe # Length 0 Object Plano Infinity 1 Ape. Stop Plano −0.459 2 Lens 1 4.0496 ASP 1.729 Plastic 1.545 56.1 8.38 3 30.3592 ASP 1.042 4 Lens 2 −2.8902 ASP 1.133 Plastic 1.660 20.4 −4.53 5 −99.0460 ASP 0.199 6 Lens 3 1.9693 ASP 0.485 Plastic 1.669 19.5 12.32 7 2.3322 ASP 0.426 8 Stop Plano −0.152 9 Lens 4 3.7932 ASP 0.988 Plastic 1.587 28.3 10.99 10 8.3147 ASP 6.411 11 Filter Plano 0.210 Glass 1.517 64.2 — 12 Plano 1.021 13 Image Plano — Reference wavelength is 587.6 nm (d-line). Effective radius of Surface 8 (Stop S1) is 2.04 mm.

TABLE 9B Aspheric Coefficients Surface # 2 3 4 5 k= −6.84354000E−01 −4.99986000E+00 −1.45672000E+01 −9.90000000E+01 A4=  1.24873470E−03  5.70856650E−03 −4.90200650E−03 −1.61760680E−02 A6= −2.04338070E−04 −2.01710990E−03  1.36068910E−02  1.84641520E−02 A8=  6.58876310E−05  1.15296520E−03 −8.75253140E−03 −9.07007980E−03 A10= −1.77084860E−05 −5.23182390E−04  3.51911970E−03  2.58581820E−03 A12=  1.75739120E−06  1.44325970E−04 −8.76176120E−04 −4.06744080E−04 A14= −9.42045180E−08 −2.26173700E−05  1.22056780E−04  2.64617630E−05 A16=  1.51996130E−06 −7.19626820E−06  2.24741310E−07 Surface # 6 7 9 10 k= −6.24954000E+00 −7.26020000E+00  1.44123000E+00  4.91521000E−01 A4= −1.46897280E−03 −7.09834400E−03 −3.99282580E−02 −9.52100400E−03 A6= −1.40415190E−02 −8.54389930E−03  1.14112050E−02  8.11923130E−04 A8=  1.24611060E−02  8.26671290E−03 −6.40551840E−03 −1.10123090E−03 A10= −6.26382700E−03 −3.96013890E−03  2.52795010E−03  4.54462880E−04 A12=  1.75760440E−03  1.00837000E−03 −7.08813200E−04 −1.08814580E−04 A14= −2.59847460E−04 −1.26390440E−04  1.17013870E−04  1.44100380E−05 A16=  1.59673650E−05  6.40330660E−06 −8.04062750E−06 −8.23152420E−07

In the 9th embodiment, the equation of the aspheric surface profiles of the aforementioned lens elements is the same as the equation of the 1st embodiment. Also, the definitions of these parameters shown in the following table are the same as those stated in the 1st embodiment with corresponding values for the 9th embodiment, so an explanation in this regard will not be provided again.

Moreover, these parameters can be calculated from Table 9A and Table 9B as the following values and satisfy the following conditions:

9th Embodiment f [mm] 12.26 TD/BL 0.77 Fno 3.15 ΣAT/ΣCT 0.35 HFOV [deg.] 15.0 T23/T12 0.19 (R3 + R4)/(R3 − R4) −1.06 CT3/CT1 0.28 |R1/R2| 0.13 CT4/CT1 0.57 |f1/f3| + |f1/f4| 1.44 CT4/CT2 0.87 |f1/f4| 0.76 (CT3 + CT4)/CT1 0.85 |f2/f4| 0.41 f2/CT2 −4.00 f/f2 −2.70 V4/V2 1.39 SD/TD 0.92 Y1R1/Y4R2 0.87

10th Embodiment

FIG. 19 is a three-dimensional schematic view of an imaging apparatus 100 according to the 10th embodiment of the present disclosure. In FIG. 19 , the imaging apparatus 100 of the 10th embodiment is a camera module, the imaging apparatus 100 includes an imaging lens assembly 101, a driving apparatus 102 and an image sensor 103, wherein the imaging lens assembly 101 includes the imaging system lens assembly of the present disclosure and a lens barrel (its reference number is omitted) for carrying the imaging system lens assembly. The imaging apparatus 100 can focus light from an imaged object via the imaging lens assembly 101, perform image focusing by the driving apparatus 102, and generate an image on the image sensor 103, and the imaging information can be transmitted.

The driving apparatus 102 can be an auto-focus module, which can be driven by driving systems, such as voice coil motors (VCM), micro electro-mechanical systems (MEMS), piezoelectric systems, and shape memory alloys etc. The imaging system lens assembly can obtain a favorable imaging position by the driving apparatus 102 so as to capture clear images when the imaged object is disposed at different object distances.

The imaging apparatus 100 can include the image sensor 103 located on the image surface of the imaging system lens assembly, such as CMOS and CCD, with superior photosensitivity and low noise. Thus, it is favorable for providing realistic images with high definition image quality thereof. Moreover, the imaging apparatus 100 can further include an image stabilization module 104, which can be a kinetic energy sensor, such as an accelerometer, a gyro sensor, and a Hall Effect sensor. In the 10th embodiment, the image stabilization module 104 is a gyro sensor, but is not limited thereto. Therefore, the variation of different axial directions of the imaging system lens assembly can adjusted so as to compensate the image blur generated by motion at the moment of exposure, and it is further favorable for enhancing the image quality while photographing in motion and low light situation. Furthermore, advanced image compensation functions, such as optical image stabilizations (01S) and electronic image stabilizations (EIS) etc., can be provided.

11th Embodiment

FIG. 20A is a schematic view of one side of an electronic device 200 according to the 11th embodiment of the present disclosure. FIG. 20B is a schematic view of another side of the electronic device 200 of FIG. 20A. FIG. 20C is a system schematic view of the electronic device 200 of FIG. 20A. In FIG. 20A, FIG. 20B and FIG. 20C, the electronic device 200 according to the 11th embodiment is a smartphone, which include imaging apparatuses 100, 110, 120, 130, 140, a flash module 201, a focusing assisting module 202, an image signal processor (ISP) 203, a user interface 204 and an image software processor 205, wherein each of the imaging apparatuses 120, 130, 140 is a front camera. When the user captures images of an imaged object 206 via the user interface 204, the electronic device 200 focuses and generates an image via at least one of the imaging apparatuses 100, 110, 120, 130, 140, while compensating for low illumination via the flash module 201 when necessary. Then, the electronic device 200 quickly focuses on the imaged object 206 according to its object distance information provided by the focusing assisting module 202, and optimizes the image via the image signal processor 203 and the image software processor 205. Thus, the image quality can be further enhanced. The focusing assisting module 202 can adopt conventional infrared or laser for obtaining quick focusing, and the user interface 204 can utilize a touch screen or a physical button for capturing and processing the image with various functions of the image processing software.

Each of the imaging apparatuses 100, 110, 120, 130, 140 according to the 11th embodiment can include the imaging system lens assembly of the present disclosure, and can be the same or similar to the imaging apparatus 100 according to the aforementioned 10th embodiment, and will not describe again herein. In detail, according to the 11th embodiment, the imaging apparatuses 100, 110 can be wide angle imaging apparatus and ultra-wide angle imaging apparatus, respectively. The imaging apparatuses 120, 130, 140 can be wide angle imaging apparatus, ultra-wide angle imaging apparatus and TOF (Time-Of-Flight) module, respectively, or can be others imaging apparatuses, which will not be limited thereto. Further, the connecting relationships between each of the imaging apparatuses 110, 120, 130, 140 and other elements can be the same as the imaging apparatus 100 in FIG. 20C, or can be adaptively adjusted according to the type of the imaging apparatuses, which will not be shown and detailed descripted again.

12th Embodiment

FIG. 21 is a schematic view of one side of an electronic device 300 according to the 12th embodiment of the present disclosure. According to the 12th embodiment, the electronic device 300 is a smartphone, which include imaging apparatuses 310, 320, 330 and a flash module 301.

The electronic device 300 according to the 12th embodiment can include the same or similar elements to that according to the 11th embodiment, and each of the imaging apparatuses 310, 320, 330 according to the 12th embodiment can have a configuration which is the same or similar to that according to the 11th embodiment, and will not describe again herein. In detail, according to the 12th embodiment, each of the imaging apparatuses 310, 320, 330 can include the imaging system lens assembly of the present disclosure, and can be the same or similar to the imaging apparatus 100 according to the aforementioned 10th embodiment, and will not describe again herein. In detail, the imaging apparatus 310 can be ultra-wide angle imaging apparatus, the imaging apparatus 320 can be wide angle imaging apparatus, the imaging apparatus 330 can be telephoto imaging apparatus (which can include light path folding element), or can be adaptively adjusted according to the type of the imaging apparatuses, which will not be limited to the arrangement.

13th Embodiment

FIG. 22 is a schematic view of one side of an electronic device 400 according to the 13th embodiment of the present disclosure. According to the 13th embodiment, the electronic device 400 is a smartphone, which include imaging apparatuses 410, 420, 430, 440, 450, 460, 470, 480, 490 and a flash module 401.

The electronic device 400 according to the 13th embodiment can include the same or similar elements to that according to the 11th embodiment, and each of the imaging apparatuses 410, 420, 430, 440, 450, 460, 470, 480, 490 and the flash module 401 can have a configuration which is the same or similar to that according to the 11th embodiment, and will not describe again herein. In detail, according to the 13th embodiment, each of the imaging apparatuses 410, 420, 430, 440, 450, 460, 470, 480, 490 can include the imaging system lens assembly of the present disclosure, and can be the same or similar to the imaging apparatus 100 according to the aforementioned 10th embodiment, and will not describe again herein.

In detail, each of the imaging apparatuses 410, 420 can be ultra-wide angle imaging apparatus, each of the imaging apparatuses 430, 440 can be wide angle imaging apparatus, each of the imaging apparatuses 450, 460 can be telephoto imaging apparatus, each of the imaging apparatuses 470, 480 can be telephoto imaging apparatus (which can include light path folding element), the imaging apparatus 490 can be TOF module, or can be adaptively adjusted according to the type of the imaging apparatuses, which will not be limited to the arrangement.

14th Embodiment

FIG. 23A is a schematic view of one side of an electronic device 500 according to the 14th embodiment of the present disclosure. FIG. 23B is a schematic view of another side of the electronic device 500 of FIG. 23A. In FIG. 23A and FIG. 23B, according to the 14th embodiment, the electronic device 500 is a smartphone, which include imaging apparatuses 510, 520, 530, 540 and a user interface 504.

The electronic device 500 according to the 14th embodiment can include the same or similar elements to that according to the 11th embodiment, and each of the imaging apparatuses 510, 520, 530, 540 and the user interface 504 can have a configuration which is the same or similar to that according to the 11th embodiment, and will not describe again herein. In detail, according to the 14th embodiment, the imaging apparatus 510 corresponds to a non-circular opening located on an outer side of the electronic device 500 for capturing the image, and the imaging apparatuses 520, 530, 540 can be telephoto imaging apparatus, wide angle imaging apparatus and ultra-wide angle imaging apparatus, respectively, or can be adaptively adjusted according to the type of the imaging apparatuses, which will not be limited to the arrangement.

The foregoing description, for purpose of explanation, has been described with reference to specific embodiments. It is to be noted that Tables show different data of the different embodiments; however, the data of the different embodiments are obtained from experiments. The embodiments were chosen and described in order to best explain the principles of the disclosure and its practical applications, to thereby enable others skilled in the art to best utilize the disclosure and various embodiments with various modifications as are suited to the particular use contemplated. The embodiments depicted above and the appended drawings are exemplary and are not intended to be exhaustive or to limit the scope of the present disclosure to the precise forms disclosed. Many modifications and variations are possible in view of the above teachings. 

What is claimed is:
 1. An imaging system lens assembly comprising four lens elements, the four lens elements being, in order from an object side to an image side along an optical path: a first lens element, a second lens element, a third lens element and a fourth lens element; each of the four lens elements has an object-side surface towards the object side and an image-side surface towards the image side; wherein the second lens element has negative refractive power, the object-side surface of the second lens element is concave in a paraxial region thereof; the object-side surface of the third lens element is convex in a paraxial region thereof, the image-side surface of the third lens element is concave in a paraxial region thereof; wherein the imaging system lens assembly further comprises an aperture stop, an axial distance between the aperture stop and the image-side surface of the fourth lens element is SD, a curvature radius of the object-side surface of the second lens element is R3, a curvature radius of the image-side surface of the second lens element is R4, an axial distance between the object-side surface of the first lens element and the image-side surface of the fourth lens element is TD, an axial distance between the image-side surface of the fourth lens element and an image surface is BL, a sum of all axial distances between adjacent lens elements of the imaging system lens assembly is ΣAT, a sum of all central thicknesses of the four lens elements of the imaging system lens assembly is ΣCT, a focal length of the first lens element is f1, a focal length of the second lens element is f2, a focal length of the third lens element is f3, a focal length of the fourth lens element is f4, and the following conditions are satisfied: (R3+R4)/(R3−R4)<0; 0.1<SD/TD<2.0; 0.1<TD/BL<1.0; 0.04<ΣAT/ΣCT<0.8; 0<|f2/f4|<1.4; and 0.18<|f1/f31+|f1/f4|<1.75.
 2. The imaging system lens assembly of claim 1, wherein the first lens element has positive refractive power, the object-side surface of the first lens element is convex in a paraxial region thereof.
 3. The imaging system lens assembly of claim 1, wherein half of a maximum field of view of the imaging system lens assembly is HFOV, and the following condition is satisfied: 5.0 degrees<HFOV<20.5 degrees.
 4. The imaging system lens assembly of claim 1, wherein there is an air gap between each of adjacent lens elements of the four lens elements of the imaging system lens assembly, a central thickness of the first lens element is CT1, a central thickness of the fourth lens element is CT4, and the following condition is satisfied: 0.1<CT4/CT1<0.8.
 5. The imaging system lens assembly of claim 1, wherein a focal length of the imaging system lens assembly is f, the focal length of the second lens element is f2, and the following condition is satisfied: −10.5<f/f2<−0.75.
 6. The imaging system lens assembly of claim 1, wherein an Abbe number of the second lens element is V2, an Abbe number of the fourth lens element is V4, and the following condition is satisfied: 0.01<V4/V2<2.5.
 7. The imaging system lens assembly of claim 1, wherein at least one of the object-side surface and the image-side surface of at least one of the four lens elements comprises at least one inflection point.
 8. The imaging system lens assembly of claim 1, further comprising: a reflective element disposed between an imaged object and the image surface.
 9. The imaging system lens assembly of claim 8, wherein the reflective element is disposed at an object side of the object-side surface of the first lens element or at an image side of the image-side surface of the fourth lens element.
 10. An imaging apparatus, comprising: the imaging system lens assembly of claim 1; and an image sensor disposed on the image surface of the imaging system lens assembly.
 11. An electronic device, comprising: the imaging apparatus of claim
 10. 12. An imaging system lens assembly comprising four lens elements, the four lens elements being, in order from an object side to an image side along an optical path: a first lens element, a second lens element, a third lens element and a fourth lens element; each of the four lens elements has an object-side surface towards the object side and an image-side surface towards the image side; wherein the second lens element has negative refractive power, the object-side surface of the second lens element is concave in a paraxial region thereof; the object-side surface of the third lens element is convex in a paraxial region thereof, the image-side surface of the third lens element is concave in a paraxial region thereof; wherein there is an air gap between each of adjacent lens elements of the four lens elements of the imaging system lens assembly; the imaging system lens assembly further comprises an aperture stop, an axial distance between the aperture stop and the image-side surface of the fourth lens element is SD, a curvature radius of the object-side surface of the second lens element is R3, a curvature radius of the image-side surface of the second lens element is R4, an axial distance between the object-side surface of the first lens element and the image-side surface of the fourth lens element is TD, an axial distance between the image-side surface of the fourth lens element and an image surface is BL, an axial distance between the first lens element and the second lens element is T12, an axial distance between the second lens element and the third lens element is T23, a focal length of the second lens element is f2, a focal length of the fourth lens element is f4, a central thickness of the first lens element is CT1, a central thickness of the third lens element is CT3, a central thickness of the fourth lens element is CT4, and the following conditions are satisfied: (R3+R4)/(R3−R4)<0; 0.1<SD/TD<2.0; 0.1<TD/BL<1.0; 0.01<T23/T12<30.0; 0<|f2/f4|<0.95; and 0.1<(CT3+CT4)/CT1<1.5.
 13. The imaging system lens assembly of claim 12, wherein half of a maximum field of view of the imaging system lens assembly is HFOV, and the following condition is satisfied: 5.0 degrees<HFOV<20.5 degrees.
 14. The imaging system lens assembly of claim 12, wherein an f-number of the imaging system lens assembly is Fno, and the following condition is satisfied: 2.0<Fno<4.5.
 15. The imaging system lens assembly of claim 12, wherein the focal length of the second lens element is f2, a central thickness of the second lens element is CT2, and the following condition is satisfied: −10.0<f2/CT2<−3.0.
 16. The imaging system lens assembly of claim 12, wherein the central thickness of the first lens element is CT1, a central thickness of the second lens element is CT2, the central thickness of the third lens element is CT3, the central thickness of the fourth lens element is CT4, and the following conditions are satisfied: 0.1<CT4/CT2<1.0; and 0.1<CT3/CT1<1.0.
 17. The imaging system lens assembly of claim 12, wherein a focal length of the first lens element is f1, a focal length of the third lens element is f3, the focal length of the fourth lens element is f4, and the following condition is satisfied: 0.18<|f1/f31+|f1/f4|<1.75.
 18. The imaging system lens assembly of claim 12, wherein at least one of the object-side surface and the image-side surface of at least one of the four lens elements comprises at least one inflection point.
 19. An imaging system lens assembly comprising four lens elements, the four lens elements being, in order from an object side to an image side along an optical path: a first lens element, a second lens element, a third lens element and a fourth lens element; each of the four lens elements has an object-side surface towards the object side and an image-side surface towards the image side; wherein the second lens element has negative refractive power, the object-side surface of the second lens element is concave in a paraxial region thereof; the object-side surface of the third lens element is convex in a paraxial region thereof, the image-side surface of the third lens element is concave in a paraxial region thereof; wherein a curvature radius of the object-side surface of the second lens element is R3, a curvature radius of the image-side surface of the second lens element is R4, an axial distance between the object-side surface of the first lens element and the image-side surface of the fourth lens element is TD, an axial distance between the image-side surface of the fourth lens element and an image surface is BL, an axial distance between the first lens element and the second lens element is T12, an axial distance between the second lens element and the third lens element is T23, a focal length of the imaging system lens assembly is f, a focal length of the first lens element is f1, a focal length of the second lens element is f2, a focal length of the fourth lens element is f4, and the following conditions are satisfied: (R3+R4)/(R3−R4)<0; 0.1<TD/BL<1.0; 0.01<T23/T12<20.0; −10.5<f/f2<−0.75; and 0<|f1/f4|<0.87.
 20. The imaging system lens assembly of claim 19, wherein half of a maximum field of view of the imaging system lens assembly is HFOV, and the following condition is satisfied: 5.0 degrees<HFOV<20.5 degrees.
 21. The imaging system lens assembly of claim 19, wherein there is an air gap between each of adjacent lens elements of the four lens elements of the imaging system lens assembly, a curvature radius of the object-side surface of the first lens element is R1, a curvature radius of the image-side surface of the first lens element is R2, and the following condition is satisfied: 0<|R1/R21<0.7.
 22. The imaging system lens assembly of claim 19, wherein an Abbe number of the second lens element is V2, an Abbe number of the fourth lens element is V4, and the following condition is satisfied: 0.01<V4/V2<2.5.
 23. The imaging system lens assembly of claim 19, wherein the focal length of the second lens element is f2, a central thickness of the second lens element is CT2, and the following condition is satisfied: −10.0<f2/CT2<−3.0.
 24. The imaging system lens assembly of claim 19, wherein a sum of all axial distances between adjacent lens elements of the imaging system lens assembly is ΣAT, a sum of all central thicknesses of the four lens elements of the imaging system lens assembly is ΣCT, and the following condition is satisfied: 0.04<ΣAT/ΣCT<0.8.
 25. The imaging system lens assembly of claim 19, wherein a height of a maximum effective radius of the object-side surface of the first lens element is Y1R1, a height of a maximum effective radius of the image-side surface of the fourth lens element is Y4R2, and the following condition is satisfied: 0.7<Y1R1/Y4R2<1.6.
 26. The imaging system lens assembly of claim 19, wherein at least one of the object-side surface and the image-side surface of at least one of the four lens elements comprises at least one inflection point.
 27. The imaging system lens assembly of claim 19, further comprising: an aperture stop disposed between an imaged object and the second lens element. 